SECURITIES & EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Name of Issuer)

(Title of Class of Securities)

(CUSIP Number)

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition which is the subject of this Schedule 13D, and is filing this schedule because of Rule 13d-1(e), Rule 13d-1(f) or Rule 13d-1(g), check the following box  ¨.

NOTE: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7(b) for other parties to whom copies are to be sent.

The information required on the remainder of this cover page shall not be deemed to be “filed” for purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No.: 750875304

This Schedule 13D is filed with respect to the common stock, $0.0001 par value, of Rainmaker Systems, Inc., a Delaware corporation (the “Issuer”). The principal executive offices of the Issuer are located at 900 East Hamilton Ave., Suite 400, Campbell, CA 95008.

c/o Rainmaker Systems, Inc.

900 East Hamilton Ave., Suite 400

Campbell, CA 95008

Pursuant to those certain subscription agreements, dated June 22, 2011, by and between the Issuer and the investors party thereto (the “Subscription Agreements”), a form of which is filed as Exhibit 1 to this Schedule 13D and incorporated herein by reference, the Issuer agreed to sell 3,669,709 shares of its common stock together with warrants to purchase up to 1,467,887 additional shares of its common stock (the “Offering”). The source of the funds for the Reporting Person’s acquisition of securities in the Offering was personal funds. The Reporting Person did not acquire beneficial ownership of any shares in the Offering with borrowed funds.

The Reporting Person has acquired the shares of the Issuer’s common stock for investment purposes, and such purchases have been made in the Reporting Person’s ordinary course of business. The Reporting Person remains a passive investor and would be permitted to file a Schedule 13G but for his previous acquisition of beneficial ownership of more than 2% of the shares of the Issuer’s common stock during a 12-month period. (See Item 5.c below.)

The Reporting Person reserves the right to formulate plans and/or make proposals, and take such actions with respect to his investment in the Issuer, including any or all of the actions set forth in paragraphs (a) through (j)

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of Item 4 of Schedule 13D, or acquire additional shares of the Issuer’s common stock or dispose of all of the shares of the Issuer’s common stock beneficially owned by him, in the public market or privately negotiated transactions. The Reporting Person may at any time reconsider and change his plans or proposals relating to the foregoing.

The Reporting Person filed an Amendment No. 1 to Statement on Schedule 13G/A with the Securities and Exchange Commission (the “SEC”) on February 2, 2002 (the “First Amendment”) which amended and supplemented the initial Schedule 13G filed by the Reporting Person with the SEC on February 16, 2000. As of the filing of the First Amendment, the Reporting Person was the beneficial owner of 1,147,262 shares of the Issuer’s common stock, which represented approximately 15% of the shares of the Issuer’s common stock (as adjusted to reflect the 1-for-5 reverse stock split effected on December 15, 2005) outstanding as of December 31, 2001. Below is a chart reflecting the Reporting Person’s annual beneficial ownership of shares of the Issuer’s common stock since the filing of the First Amendment. The Reporting Person may be deemed to have exercised sole voting and dispositive power over all of the shares listed in the chart.

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(1) The Reporting Person’s beneficial ownership percentage is based on an aggregate of 7,731,389 shares of the Issuer’s common stock outstanding as of February 28, 2002, as disclosed in the Issuer’s proxy statement on Schedule 14A filed with the SEC on April 14, 2002, and 25,000 shares of the Issuer’s common stock which could have been acquired by the Reporting Person pursuant to stock options and warrants to purchase common stock that were exercisable within 60 days of February 28, 2002, as adjusted to reflect the 1-for-5 reverse stock split effected on December 15, 2005.

(2) The Reporting Person’s beneficial ownership percentage is based on an aggregate of 7,766,719 shares of the Issuer’s common stock outstanding as of February 28, 2003, as disclosed in the Issuer’s proxy statement on Schedule 14A filed with the SEC on April 16, 2003, and 57,500 shares of the Issuer’s common stock which could have been acquired by the Reporting Person pursuant to stock options and warrants to purchase common stock that were exercisable within 60 days of February 28, 2003, as adjusted to reflect the 1-for-5 reverse stock split effected on December 15, 2005.

(3) The Reporting Person’s beneficial ownership percentage is based on an aggregate of 8,812,091 shares of the Issuer’s common stock outstanding as of February 27, 2004, as disclosed in the Issuer’s proxy statement on Schedule 14A filed with the SEC on March 23, 2004, and 87,500 shares of the Issuer’s common stock which could have been acquired by the Reporting Person pursuant to stock options and warrants to purchase common stock that were exercisable within 60 days of February 27, 2004, as adjusted to reflect the 1-for-5 reverse stock split effected on December 15, 2005.

(4) The Reporting Person’s beneficial ownership percentage is based on an aggregate of 9,552,852 shares of the Issuer’s common stock outstanding as of February 28, 2005, as disclosed in the Issuer’s proxy statement on Schedule 14A filed with the SEC on April 18, 2005, and 112,520 shares of the Issuer’s common stock which could have been acquired by the Reporting Person pursuant to stock options and warrants to purchase common stock that were exercisable within 60 days of February 28, 2005, as adjusted to reflect the 1-for-5 reverse stock split effected on December 15, 2005.

(5) The Reporting Person’s beneficial ownership percentage is based on an aggregate of 13,332,772 shares of the Issuer’s common stock outstanding as of February 28, 2006, as disclosed in the Issuer’s proxy statement on Schedule 14A filed with the SEC on April 21, 2006, and 282,000 shares of the Issuer’s common stock which could have been acquired by the Reporting Person pursuant to stock options and warrants to purchase common stock that were exercisable within 60 days of February 28, 2006.

(6) The Reporting Person’s beneficial ownership percentage is based on an aggregate of 15,175,812 shares of the Issuer’s common stock outstanding as of February 28, 2007, as disclosed in the Issuer’s proxy statement on Schedule 14A filed with the SEC on April 12, 2007, and 282,000 shares of the Issuer’s common stock which could have been acquired by the Reporting Person pursuant to stock options and warrants to purchase common stock that were exercisable within 60 days of February 28, 2007.

(7) The Reporting Person’s beneficial ownership percentage is based on an aggregate of 20,348,338 shares of the Issuer’s common stock outstanding as of February 29, 2008, as disclosed in the Issuer’s proxy statement on Schedule 14A filed with the SEC on April 15, 2008, and 261,999 shares of the Issuer’s common stock which could have been acquired by the Reporting Person pursuant to stock options and warrants to purchase common stock that were exercisable within 60 days of February 29, 2008.

(8) The Reporting Person’s beneficial ownership percentage is based on an aggregate of 21,866,885 shares of the Issuer’s common stock outstanding as of February 28, 2009, as disclosed in the Issuer’s proxy statement on Schedule 14A filed with the SEC on April 13, 2009, and 261,999 shares of the Issuer’s common stock which could have been acquired by the Reporting Person pursuant to stock options and warrants to purchase common stock that were exercisable within 60 days of February 28, 2009.

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(9) The Reporting Person’s beneficial ownership percentage is based on an aggregate of 22,489,644 shares of the Issuer’s common stock outstanding as of February 28, 2010, as disclosed in the Issuer’s proxy statement on Schedule 14A filed with the SEC on April 9, 2010, and 101,999 shares of the Issuer’s common stock which could have been acquired by the Reporting Person pursuant to stock options and warrants to purchase common stock that were exercisable within 60 days of February 28, 2010.

The Reporting Person serves as the chief executive officer and president of the Issuer. The Reporting Person entered into an employment agreement, dated January 1, 2001, as amended, with the Issuer (the “Employment Agreement”), which is filed as Exhibit 2 to this Schedule 13D and incorporated herein by reference.

The Reporting Person has previously been granted stock options and restricted stock and may be granted additional stock options and restricted stock at a future date pursuant to the Issuer’s 2003 Stock Incentive Plan (the “2003 Plan”), which provides for the issuance of incentive stock options or nonqualified stock options to employees and issuance of shares of common stock for purchase or as a bonus for services rendered (restricted stock awards). Options granted under the 2003 Plan are priced at not less than 100% of the fair value of the common stock on the date of grant and have a maximum term of ten years from the date of grant. Options granted to employees become exercisable and vest in one or more installments over varying periods ranging up to five years as specified by the board of directors. Restricted stock awards granted to employees typically vest over a one to four year period from the date of grant.

The foregoing description of the terms of the 2003 Plan is qualified in its entirety by reference to the copy of the 2003 Plan, which is filed as Exhibit 3 to this Schedule 13D and incorporated herein by reference.

Pursuant to the Offering, the Reporting Person entered into a Lock-up Agreement, dated June 22, 2011, with the Issuer. Under the Lock-up Agreement, the shares of the Issuer’s common stock held by the Reporting Person may not be sold, directly or indirectly, on or before the date 90 days after the closing of the Offering, subject to certain exceptions.

The foregoing description of the terms of the Lock-up Agreement is qualified in its entirety by reference to the copy of the Lock-up Agreement, which is filed as Exhibit 4 to this Schedule 13D and incorporated herein by reference.

Pursuant to the Offering, the Reporting Person was issued a Warrant by the Issuer on June 27, 2011, entitling him to purchase, subject to the provisions of the Warrant, from the Issuer, at any time after December 27, 2011, but not later than June 24, 2016, 23,256 shares of the Issuer’s common stock at an exercise price per share equal to $1.40, subject to adjustment from time to time.

The foregoing description of the terms of the Warrant is qualified in its entirety by reference to the copy of the Warrant, which is filed as Exhibit 5 to this Schedule 13D and incorporated herein by reference.

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SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Signature Page to Schedule 13D

Exhibit 4

CUSIP No.: 750875304

Lock-Up Agreement

June 22, 2011

Merriman Capital, Inc.

135 East 57th Street

24th Floor

New York, New York 10022

Ladies and Gentlemen:

The undersigned understands that Merriman Capital, Inc. (the “Placement Agent”) proposes to enter into a Placement Agent Agreement (the “Placement Agent Agreement”) with Rainmaker Systems Inc., a Delaware corporation (the “Company”), relating to the offering (the “Offering”) of up to 3,675,182 of shares (the “Shares”) of the Common Stock of the Company, par value $0.001 per share (the “Common Stock”) and warrants (the “Warrants”) to purchase up to 1,470,073 shares of Common Stock. Capitalized terms used herein and not otherwise defined shall have the meanings set forth in the Placement Agent Agreement.

In consideration of the foregoing, and in order to induce you to participate as the placement agent in the Offering, and for other good and valuable consideration receipt of which is hereby acknowledged, the undersigned hereby agrees that, without the prior written consent of the Placement Agent (which consent may be withheld in its sole discretion), the undersigned will not, during the period (the “Lock-Up Period”) beginning on the date hereof and ending on the earlier of (i) the date 90 days after the date of the final prospectus (including the final prospectus supplement) to be used in confirming the sale of the Shares (the “Final Prospectus”) or (ii) the termination of the Placement Agent Agreement by the Placement Agent prior to the Closing (other than as a result of any breach of Section 4(n) of the Placement Agent Agreement), (1) offer, pledge, announce the intention to sell, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, or otherwise transfer or dispose of, directly or indirectly, or file (or participate in the filing of) a registration statement with the Securities and Exchange Commission in respect of, any shares of Common Stock or any securities convertible into or exercisable or exchangeable for shares of Common Stock (including without limitation, shares of Common Stock which may be deemed to be beneficially owned by the undersigned in accordance with the rules and regulations of the Securities and Exchange Commission and securities which may be issued upon exercise of a stock option or warrant), (2) enter into any swap or other agreement that transfers, in whole or in part, any of the economic consequences of ownership of the shares of, whether any such transaction described in clause (1) or (2) above is to be settled by delivery of shares of Common Stock or such other securities, in cash or otherwise, (3) make any demand for or exercise any right with respect to, the registration of any shares of Common Stock or any security convertible into or exercisable or exchangeable for shares of Common Stock, or (4) publicly announce an intention to effect any transaction specific in clause (1), (2) or (3) above.

CUSIP No.: 750875304

Notwithstanding the foregoing, the restrictions set forth in clause (1) and (2) above shall not apply to (a) transfers (i) as a bona fide gift or gifts, provided that the donee or donees thereof agree to be bound in writing by the restrictions set forth herein, (ii) to any trust for the direct or indirect benefit of the undersigned or the immediate family of the undersigned, provided that the trustee of the trust agrees to be bound in writing by the restrictions set forth herein, and provided further that any such transfer shall not involve a disposition for value or (iii) with your prior written consent, (b) the acquisition or exercise of any stock option issued pursuant to the Company’s existing stock option plan, including any exercise effected by the delivery of shares of Common Stock of the Company held by the undersigned, or (c) the purchase or sale of the Company’s securities pursuant to a plan, contract or instruction that satisfies all of the requirements of Rule 10b5-1(c)(1)(i)(B) that was in effect prior to the date hereof. For purposes of this Lock-Up Agreement, “immediate family” shall mean any relationship by blood, marriage or adoption, not more remote than first cousin. None of the restrictions set forth in this Lock-Up Agreement shall apply to shares of Common Stock acquired in open market transactions.

For the purpose of allowing the Placement Agent to comply with FINRA Rule 2711(f)(4), if (1) during the last 17 days of the Lock-Up Period, the Company releases earnings results or publicly announces other material news or a material event relating to the Company occurs or (2) prior to the expiration of the Lock-Up Period, the Company announces that it will release earnings results during the 16 day period beginning on the last day of the Lock-Up Period, then in each case the Lock-Up Period will be extended until the expiration of the 18 day period beginning on the date of release of the earnings results or the public announcement regarding the material news or the occurrence of the material event, as applicable, unless the Placement Agent waives, in writing, such extension. The Placement Agent agrees to waive such extension if the provisions of FINRA Rule 2711(f)(4) are not applicable to the Offering. The undersigned acknowledges that the Company has agreed not to accelerate the vesting of any option or warrant or the lapse of any repurchase right prior to the expiration of the Lock-Up Period, except in accordance with the terms of any existing employment agreement. In furtherance of the foregoing, the Company, and any duly appointed transfer agent or depositary for the registration or transfer of the securities described herein, are hereby authorized to decline to make any transfer of securities if such transfer would constitute a violation or breach of this Lock-Up Agreement.

The foregoing restrictions are expressly agreed to preclude the undersigned from engaging in any hedging or other transaction which is designed to or reasonably expected to lead to or result in a sale or disposition of shares of Common Stock even if such securities would be disposed of by someone other than the undersigned. Such prohibited hedging or other transactions would include without limitation any short sale or any purchase, sale or grant of any right (including without limitation any put option or put equivalent position or call option or call equivalent position) with respect to any of the shares of Common Stock or with respect to any security that includes, relates to, or derives any significant part of its value from such shares.

The undersigned hereby represents and warrants that the undersigned has full power and authority to enter into this Lock-Up Agreement. All authority herein conferred or agreed to be conferred and any obligations of the undersigned shall be binding upon the successors, assigns, heirs or personal representatives of the undersigned.

The undersigned also agrees and consents to the entry of stop transfer instructions with the Company’s transfer agent and registrar or depositary against the transfer of the undersigned’s shares of Common Stock except in compliance with the foregoing restrictions.

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The undersigned understands that, if the Placement Agent Agreement does not become effective, or if the Placement Agent Agreement (other than the provisions thereof which survive termination) shall terminate or be terminated prior to payment for and delivery of the Shares to be sold thereunder, the undersigned shall be released from all obligations under this Lock-Up Agreement.

This Lock-Up Agreement shall be governed by and construed in accordance with the laws of the State of New York, without regard to the conflict of laws principles thereof.

[Signature page immediately follows]

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Exhibit 5

CUSIP No.: 750875304

Warrant

THIS WARRANT SHALL BE VOID AFTER 5:00 P.M. EASTERN TIME ON JUNE 24, 2016 (the “EXPIRATION DATE”).

No. 2011 W-49

RAINMAKER SYSTEMS, INC.

WARRANT TO PURCHASE 23,256 SHARES OF

COMMON STOCK, PAR VALUE $0.001 PER SHARE

For VALUE RECEIVED, Michael Silton TTEE Michael Silton SP Trust U/A DTD 12/13/04 (“Warrantholder”), is entitled to purchase, subject to the provisions of this Warrant, from Rainmaker Systems, Inc., a Delaware corporation (“Company”), at any time after the date that is six (6) months after the date hereof (the “Exercisability Date”), but not later than 5:00 P.M., Eastern time, on the Expiration Date (as defined above), at an exercise price per share equal to $1.40 (the exercise price in effect being herein called the “Warrant Price”), 23,256 shares (“Warrant Shares”) of the Company’s Common Stock, par value $0.001 per share (“Common Stock”). The number of Warrant Shares purchasable upon exercise of this Warrant and the Warrant Price shall be subject to adjustment from time to time as described herein. This Warrant is the warrant to purchase Common Stock, par value $0.001, of the Company issued pursuant to (i) Section 2 of that certain Subscription Agreement dated as of June 22, 2011 (the “Subscription Agreement”) by and between the Company and the Warrantholder, and (ii) the Company’s registration statement on Form S-3 (file number 333-171946).

Section 1. Registration. The Company shall maintain books for the transfer and registration of the Warrant. Upon the initial issuance of this Warrant, the Company shall issue and register the Warrant in the name of the Warrantholder.

Section 2. Transfers. The Company shall transfer this Warrant from time to time upon the books to be maintained by the Company for that purpose upon surrender of this Warrant for transfer, properly endorsed or accompanied by appropriate instructions for transfer in the form of Appendix A and such other documents as may be reasonably required by the Company, and a new Warrant shall be issued to the transferee and the surrendered Warrant shall be canceled by the Company.

Section 3. Exercise of Warrant.

(a) Subject to the provisions hereof, the Warrantholder may exercise this Warrant in whole or in part, at any time after the Exercisability Date and prior to the expiration of the Warrant, upon surrender of the Warrant, together with delivery of the duly executed Warrant exercise form attached hereto as Appendix B (the “Exercise Agreement”) and payment

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by cash, certified check or wire transfer of funds for the aggregate Warrant Price for that number of Warrant Shares then being purchased, to the Company during normal business hours on any business day at the Company’s principal executive offices (or such other office or agency of the Company as it may designate by notice to the Warrantholder). The Warrant Shares so purchased shall be deemed to be issued to the Warrantholder or the Warrantholder’s designee, as the record owner of such shares, as of the close of business on the date on which this Warrant shall have been surrendered (or evidence of loss, theft or destruction thereof and security or indemnity satisfactory to the Company), the Warrant Price shall have been paid and the completed Exercise Agreement shall have been delivered (such items and payment, the “Exercise Deliverables”).

(b) On or before the third (3rd) business day following the date on which the Company has received the Exercise Deliverables, the Company shall (i) provided that the Company’s transfer agent is participating in The Depository Trust Company (“DTC”) Fast Automated Securities Transfer Program, upon the request of the Warrantholder, credit such aggregate number of shares of Common Stock to which the Warrantholder is entitled pursuant to such exercise to the Warrantholder’s or its designee’s balance account with DTC through its Deposit/Withdrawal at Custodian system, or (ii) if the Company’s transfer agent is not participating in the DTC Fast Automated Securities Transfer Program, issue and deliver to the Warrantholder or, at the Warrantholder’s instruction pursuant to the Exercise Agreement, the Warrantholder’s agent or designee, in each case, sent by reputable overnight courier to the address as specified in the applicable Exercise Agreement, a certificate, registered in the Company’s share register in the name of the Warrantholder or its designee (as indicated in the applicable Exercise Agreement), for the number of shares of Common Stock to which the Warrantholder is entitled pursuant to such exercise. If this Warrant shall have been exercised only in part, then, unless this Warrant has expired, the Company shall, at its expense, at the time of delivery of such Warrant Shares or promptly thereafter, deliver to the Warrantholder a new Warrant representing the number of shares with respect to which this Warrant shall not then have been exercised. As used herein, “business day” means a day, other than a Saturday or Sunday, on which banks in New York City are open for the general transaction of business.

(c) If by the third business day after such an exercise and the Company’s receipt of the Exercise Deliverables the Company fails to deliver the required number of Warrant Shares in the manner specified herein, and if after such third business day and prior to the receipt of such Warrant Shares, the Warrantholder purchases (in an open market transaction or otherwise) shares of Common Stock to deliver in satisfaction of a sale by the Warrantholder of the Warrant Shares which the Warrantholder anticipated receiving upon such exercise (a “Buy-In”), then the Company shall (1) pay in cash to the Warrantholder the amount by which (x) the Warrantholder’s total purchase price (including brokerage commissions, if any) for the shares of Common Stock so purchased exceeds (y) the amount obtained by multiplying (A) the number of Warrant Shares that the Company was required to deliver to the Warrantholder in connection with the exercise at issue by (B) the closing sale price of the Common Stock on the date of the Company’s receipt of the Exercise Deliverables and (2) at the option of the Warrantholder, either reinstate the portion of the Warrant and equivalent number of Warrant Shares for which such exercise was not honored or deliver to the Warrantholder the number of shares of Common Stock that would have been issued had the Company timely complied with its exercise and

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delivery obligations hereunder; provided however, if the Company delivered all appropriate written directions and documents to its transfer agent within one business day of the Company’s receipt of Exercise Deliverables, the foregoing Buy-In damage obligation of the Company set forth in this sentence shall not apply to such exercise. The Warrantholder shall provide the Company prompt written notice indicating the amounts payable to the Warrantholder in respect of the Buy-In. As used herein, “closing sale price” means the last closing trade price for the Common Stock on the Nasdaq Global Market, as reported by Bloomberg, or, if the Nasdaq Global Market begins to operate on an extended hours basis and does not designate the closing trade price then the last trade price of the Common Stock prior to 4:00 p.m., New York time, as reported by Bloomberg, or, if the Nasdaq Global Market is not the principal securities exchange or trading market for the Common Stock, the last closing trade price of the Common Stock on the principal securities exchange or trading market where the Common Stock is listed or traded as reported by Bloomberg, or if the foregoing do not apply, the last closing trade price of the Common Stock in the over-the-counter market on the electronic bulletin board for the Common Stock as reported by Bloomberg, or, if no closing trade price is reported for the Common Stock by Bloomberg, the average of the bid prices of any market makers for the Common Stock as reported in the “pink sheets” by Pink Sheets LLC (formerly the National Quotation Bureau, Inc.). If the closing trade price cannot be calculated for the Common Stock on a particular date on any of the foregoing bases, the closing trade price of the Common Stock on such date shall be the fair market value as mutually determined by the Company and the Warrantholder. If the Company and the Warrantholder are unable to agree upon the fair market value pursuant to the preceding sentence, the Company and the Warrantholder shall jointly select an appraiser, who is experienced in such matters. The decision of the appraiser shall be final and conclusive, and the cost of such appraiser shall be borne equally by the Company and the Warrantholder. All of the foregoing determinations shall be appropriately adjusted for any stock dividend, stock split, stock combination or other similar transaction during the applicable calculation period.

(d) Cashless Exercise. Notwithstanding anything contained herein to the contrary, if a registration statement covering the Warrant Shares that are the subject of the Exercise Agreement is not available for the resale of such Warrant Shares, the Warrantholder may, in its sole discretion, exercise this Warrant in whole or in part and, in lieu of making the cash payment otherwise contemplated to be made to the Company upon such exercise in payment of the aggregate Warrant Price, elect instead to receive upon such exercise the “Net Number” of shares of Common Stock determined according to the following formula (a “Cashless Exercise”):

For purposes of the foregoing formula:

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(e) Rule 144. For purposes of Rule 144(d) promulgated under the Securities Act of 1933, as amended, as in effect on the date hereof, it is intended that the Warrant Shares issued in a Cashless Exercise shall be deemed to have been acquired by the Warrantholder, and the holding period for the Warrant Shares shall be deemed to have commenced, on the date this Warrant was originally issued pursuant to the Subscription Agreement.

Section 4. Payment of Taxes. The Company will pay any documentary stamp taxes attributable to the initial issuance of Warrant Shares issuable upon the exercise of the Warrant; provided, however, that the Company shall not be required to pay any tax or taxes which may be payable in respect of any transfer involved in the issuance or delivery of any certificates for Warrant Shares in a name other than that of the Warrantholder in respect of which such shares are issued, and in such case, the Company shall not be required to issue or deliver any certificate for Warrant Shares or any Warrant until the Person requesting the same has paid to the Company the amount of such tax or has established to the Company’s reasonable satisfaction that such tax has been paid. The Warrantholder shall be responsible for income taxes due under federal, state or other law, if any such tax is due.

Section 5. Mutilated or Missing Warrants. In case this Warrant shall be mutilated, lost, stolen, or destroyed, the Company shall issue in exchange and substitution of and upon cancellation of the mutilated Warrant, or in lieu of and substitution for the Warrant lost, stolen or destroyed, a new Warrant of like tenor and for the purchase of a like number of Warrant Shares, but only upon receipt of evidence reasonably satisfactory to the Company of such loss, theft or destruction of the Warrant, and with respect to a lost, stolen or destroyed Warrant, reasonable indemnity with respect thereto, if requested by the Company.

Section 6. Reservation of Common Stock. The Company hereby represents and warrants that there have been reserved, and the Company shall at all applicable times keep reserved until issued (if necessary) as contemplated by this Section 6, out of the authorized and unissued shares of Common Stock, sufficient shares to provide for the exercise of the rights of purchase represented by this Warrant. The Company agrees that all Warrant Shares issued upon due exercise of the Warrant shall be, at the time of delivery of such Warrant Shares, duly authorized, validly issued, fully paid and non-assessable shares of Common Stock of the Company.

Section 7. Adjustments. Subject and pursuant to the provisions of this Section 7, the Warrant Price and number of Warrant Shares subject to this Warrant shall be subject to adjustment from time to time as set forth hereinafter.

(a) If the Company shall, at any time or from time to time while this Warrant

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is outstanding, pay a dividend or make a distribution on its Common Stock in shares of Common Stock, subdivide its outstanding shares of Common Stock into a greater number of shares or combine its outstanding shares of Common Stock into a smaller number of shares or issue by reclassification of its outstanding shares of Common Stock any shares of its capital stock (including any such reclassification in connection with a consolidation or merger in which the Company is the continuing corporation), then the number of Warrant Shares purchasable upon exercise of the Warrant and the Warrant Price in effect immediately prior to the date upon which such change shall become effective, shall be adjusted by the Company so that the Warrantholder thereafter exercising the Warrant shall be entitled to receive the number of shares of Common Stock, or other capital stock which the Warrantholder would have received if the Warrant had been exercised immediately prior to such event, upon payment of a Warrant Price that has been adjusted to reflect a fair allocation of the economics of such event to the Warrantholder. Such adjustments shall be made successively whenever any event listed above shall occur.

(b) If any capital reorganization, reclassification of the capital stock of the Company, consolidation or merger of the Company with another entity in which the Company is not the survivor, or sale, transfer or other disposition of all or substantially all of the Company’s assets to another entity shall be effected, then, as a condition of such reorganization, reclassification, consolidation, merger, sale, transfer or other disposition, lawful and adequate provision shall be made whereby each Warrantholder shall thereafter have the right to purchase and receive upon the basis and upon the terms and conditions herein specified and in lieu of the Warrant Shares immediately theretofore issuable upon exercise of the Warrant, such shares of stock, securities or assets as would have been issuable or payable with respect to or in exchange for a number of Warrant Shares equal to the number of Warrant Shares immediately theretofore issuable upon exercise of the Warrant, had such reorganization, reclassification, consolidation, merger, sale, transfer or other disposition not taken place, and in any such case appropriate provision shall be made with respect to the rights and interests of each Warrantholder to the end that the provisions hereof (including, without limitation, provision for adjustment of the Warrant Price) shall thereafter be applicable, as nearly equivalent as may be practicable in relation to any shares of stock, securities or assets thereafter deliverable upon the exercise hereof. The Company shall not effect any such consolidation, merger, sale, transfer or other disposition unless prior to or simultaneously with the consummation thereof the successor corporation (if other than the Company) resulting from such consolidation or merger, or the corporation purchasing or otherwise acquiring such assets or other appropriate corporation or entity shall assume the obligation to deliver to the Warrantholder, at the last address of the Warrantholder appearing on the books of the Company, such shares of stock, securities or assets as, in accordance with the foregoing provisions, the Warrantholder may be entitled to purchase, and the other obligations under this Warrant. The provisions of this paragraph (b) shall similarly apply to successive reorganizations, reclassifications, consolidations, mergers, sales, transfers or other dispositions.

(c) In case the Company shall fix a payment date for the making of a distribution to all holders of Common Stock (including any such distribution made in connection with a consolidation or merger in which the Company is the continuing corporation) of evidences of indebtedness or assets (other than cash dividends or cash distributions payable out of

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consolidated earnings or earned surplus or dividends or distributions referred to in Section 7(a)), or subscription rights or warrants, the Warrant Price to be in effect after such payment date shall be determined by multiplying the Warrant Price in effect immediately prior to such payment date by a fraction, the numerator of which shall be the total number of shares of Common Stock outstanding multiplied by the closing sale price per share of Common Stock immediately prior to such payment date, less the fair market value (as determined by the Company’s Board of Directors in good faith) of said assets or evidences of indebtedness so distributed, or of such subscription rights or warrants, and the denominator of which shall be the total number of shares of Common Stock outstanding multiplied by such closing sale price per share of Common Stock immediately prior to such payment date. Such adjustment shall be made successively whenever such a payment date is fixed.

(d) An adjustment to the Warrant Price shall become effective immediately after the payment date in the case of each dividend or distribution and immediately after the effective date of each other event which requires an adjustment.

(e) In the event that, as a result of an adjustment made pursuant to this Section 7, the Warrantholder shall become entitled to receive any shares of capital stock of the Company other than shares of Common Stock, the number of such other shares so receivable upon exercise of this Warrant shall be subject thereafter to adjustment from time to time in a manner and on terms as nearly equivalent as practicable to the provisions with respect to the Warrant Shares contained in this Warrant.

Section 8. Fractional Interest. No fractional shares of Common Stock are to be issued upon the exercise of this Warrant, but rather the number of shares of Common Stock to be issued shall be rounded up to the nearest whole number.

Section 9. Benefits. Nothing in this Warrant shall be construed to give any Person (other than the Company and the Warrantholder) any legal or equitable right, remedy or claim, it being agreed that this Warrant shall be for the sole and exclusive benefit of the Company and the Warrantholder.

Section 10. Notices to Warrantholder. Upon the happening of any event requiring an adjustment of the Warrant Price, the Company shall promptly give written notice thereof to the Warrantholder at the address appearing in the records of the Company, stating the adjusted Warrant Price and the adjusted number of Warrant Shares resulting from such event and setting forth in reasonable detail the method of calculation and the facts upon which such calculation is based. Failure to give such notice to the Warrantholder or any defect therein shall not affect the legality or validity of the subject adjustment.

Section 11. Identity of Transfer Agent. The transfer agent for the Common Stock is Computershare Investor Services, LLC. Upon the appointment of any subsequent transfer agent for the Common Stock or other shares of the Company’s capital stock issuable upon the exercise of the rights of purchase represented by the Warrant, the Company will mail to the Warrantholder a statement setting forth the name and address of such transfer agent.

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CUSIP No.: 750875304

Section 12. Notices. Unless otherwise provided, any notice required or permitted under this Warrant shall be given in writing and shall be deemed effectively given as hereinafter described (i) if given by personal delivery, then such notice shall be deemed given upon such delivery, (ii) if given by telex or facsimile, then such notice shall be deemed given upon receipt of confirmation of complete transmittal, and (iii) if given by mail (whether overnight courier or US mail), then such notice shall be deemed given upon receipt of confirmation of delivery. All notices shall be addressed as follows: if to the Warrantholder, at its address as set forth in the Company’s books and records and, if to the Company, at the address as follows, or at such other address as the Warrantholder or the Company may designate by ten days’ advance written notice to the other:

If to the Company:

Rainmaker Systems, Inc.

900 East Hamilton Avenue, Suite 400

Campbell, California 95008

Attention: Mr. Timothy Burns, CFO

Fax: (408) 340-2625

With a copy to:

Paul, Hastings, Janofsky & Walker LLP

55 Second Street, 24th Floor

San Francisco, California 94105

Attention: David F. Dedyo, Esq.

Fax: (415) 856-7100

Section 13. Successors. All the covenants and provisions hereof by or for the benefit of the Warrantholder shall bind and inure to the benefit of its respective successors and assigns hereunder.

Section 14. Governing Law; Consent to Jurisdiction; Waiver of Jury Trial. This Warrant shall be governed by, and construed in accordance with, the internal laws of the State of New York, without reference to the choice of law provisions thereof. The Company and, by accepting this Warrant, the Warrantholder, each irrevocably submits to the non-exclusive jurisdiction of the courts of the State of New York located in the Borough of Manhattan and the United States District Court for the Southern District of New York for the purpose of any suit, action, proceeding or judgment relating to or arising out of this Warrant and the transactions contemplated hereby. Service of process in connection with any such suit, action or proceeding may be served on each party hereto anywhere in the world by the same methods as are specified for the giving of notices under this Warrant. The Company and, by accepting this Warrant, the Warrantholder, each irrevocably consents to the jurisdiction of any such court in any such suit, action or proceeding and to the laying of venue in such court. The Company and, by accepting this Warrant, the Warrantholder, each irrevocably waives any objection to the laying of venue of any such suit, action or proceeding brought in such courts and irrevocably waives any claim that

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CUSIP No.: 750875304

any such suit, action or proceeding brought in any such court has been brought in an inconvenient forum. EACH OF THE COMPANY AND, BY ITS ACCEPTANCE HEREOF, THE WARRANTHOLDER HEREBY WAIVES ANY RIGHT TO REQUEST A TRIAL BY JURY IN ANY LITIGATION WITH RESPECT TO THIS WARRANT AND REPRESENTS THAT COUNSEL HAS BEEN CONSULTED SPECIFICALLY AS TO THIS WAIVER.

Section 15. Restriction on Exercise. Notwithstanding anything to the contrary contained herein, the number of Warrant Shares that may be acquired by the Warrantholder upon any exercise of this Warrant (or otherwise in respect hereof) shall be limited to the extent necessary to insure that, following such exercise (or other issuance), the total number of shares of Common Stock then beneficially owned by such Warrantholder and its affiliates and any other persons whose beneficial ownership of Common Stock would be aggregated with the Warrantholder’s for purposes of Section 13(d) of the Exchange Act, does not exceed 4.999% of the total number of issued and outstanding shares of Common Stock (including for such purpose the shares of Common Stock issuable upon such exercise). For such purposes, beneficial ownership shall be determined in accordance with Section 13(d) of the Exchange Act and the rules and regulations promulgated thereunder. By written notice to the Company, a Warrantholder may waive the provisions of this Section 15 as to itself but any such waiver will not be effective until the 61st day after delivery thereof.

Section 16. No Rights as Stockholder. Prior to the exercise of this Warrant, the Warrantholder shall not have or exercise any rights as a stockholder of the Company by virtue of its ownership of this Warrant.

Section 17. Amendment; Waiver. Any term of this Warrant may be amended or waived (including the adjustment provisions included in Section 7 of this Warrant) upon the written consent of the Company and the Warrantholder.

Section 18. Section Headings. The section headings in this Warrant are for the convenience of the Company and the Warrantholder and in no way alter, modify, amend, limit or restrict the provisions hereof.

IN WITNESS WHEREOF, the Company has caused this Warrant to be duly executed, as of the 27th day of June, 2011.

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APPENDIX A

RAINMAKER SYSTEMS, INC.

ASSIGNMENT FORM

(To assign the foregoing Warrant, execute this form and supply required information. Do not use this form to purchase shares.)

FOR VALUE RECEIVED, the foregoing Warrant and all rights evidenced thereby are hereby assigned to:

Date:                          ,

Holder’s Signature:

Holder’s Address:

NOTE: The signature to this Assignment Form must correspond with the name as it appears on the face of the Warrant.

Appendix A-20

APPENDIX B

RAINMAKER SYSTEMS, INC.

WARRANT EXERCISE FORM

To Rainmaker Systems, Inc.:

The undersigned hereby irrevocably elects to exercise the right of purchase represented by the within Warrant (“Warrant”) for, and to purchase thereunder by the payment of the Warrant Price and surrender of the Warrant,                      shares of Common Stock (“Warrant Shares”) provided for therein, and requests that the Warrant Shares be issued as follows:

and, if the number of Warrant Shares shall not be all the Warrant Shares purchasable upon exercise of the Warrant, that a new Warrant for the balance of the Warrant Shares purchasable upon exercise of this Warrant be registered in the name of the undersigned Warrantholder or the undersigned’s Assignee as below indicated and delivered to the address stated below.

Dated:                     ,     

Appendix B-21

Appendix B-22