SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO

RULE 13d-1(b), (c), AND (d) AND AMENDMENTS THERETO FILED

PURSUANT TO RULE 13d-2

(Amendment No.     )

iRhythm Technologies, Inc.

(Name of Issuer)

Common Stock, $0.001 par value per share

(Title of Class of Securities)

450056106

(CUSIP Number)

December 31, 2016

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

☐ Rule 13d-1(b)

☐ Rule 13d-1(c)

☒ Rule 13d-1(d)

The information required in the remainder of this cover page shall not be deemed to be “filed” for the 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).

Schedule 13G

iRhythm Technologies, Inc. (the “Issuer”).

The Issuer’s principal executive offices are located at 650 Townsend Street, Suite 500, San Francisco, California, 94103.

This joint statement on Schedule 13G is being filed by New Leaf Ventures II, L.P. (“NLV II”), New Leaf Venture Associates II, L.P. (“NLV Associates”) and New Leaf Venture Management II, L.L.C. (“NLV Management” and together with NLV II and NLV Associates, the “Reporting Entities”) and Philippe O. Chambon (“Chambon”), Vijay Lathi (“Lathi”), Ronald Hunt (“Hunt”), Jeani Delagardelle (“Delagardelle”) and Liam Ratcliffe (“Ratcliffe” and together with Chambon, Lathi, Hunt and Delagardelle the “Managing Directors”). The Reporting Entities and the Managing Directors collectively are referred to as the “Reporting Persons”.

The address of the principal business office of NLV II, NLV Associates, NLV Management, Chambon, Hunt and Ratcliffe is New Leaf Venture Partners, Times Square Tower, 7 Times Square, Suite 3502, New York, NY 10036. The address of the principal business office of Lathi and Delagardelle is New Leaf Venture Partners, 1200 Park Place, Suite 300, San Mateo, CA 94043.

Each of NLV II and NLV Associates is a limited partnership organized under the laws of the State of Delaware. NLV Management is a limited liability company organized under the laws of the State of Delaware. Each Managing Director is a citizen of the United States.

Common Stock, $0.001 par value per share (“Common Stock”).

450056106

Not applicable.

Each Reporting Person disclaims beneficial ownership of such shares of Common Stock except for the shares, if any, such Reporting Person holds of record.

Not applicable.

Not applicable.

Not applicable.

Not applicable.

Not applicable.

Not applicable. This Schedule 13G is not filed pursuant to Rule 13d-1(b) or Rule 13d-1(c).

Material to be Filed as Exhibits.

Exhibit 1 – Agreement regarding filing of joint Schedule 13G.

Exhibit 2 – Power of Attorney regarding filings under the Securities Exchange Act of 1934, as amended.

SIGNATURES

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.

Date: February 10, 2017

EXHIBIT 1

AGREEMENT

Pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, the undersigned hereby agree that only one statement containing the information required by Schedule 13G need be filed with respect to the ownership by each of the undersigned of shares of Common Stock of iRhythm Technologies, Inc.

Date: February 10, 2017

EXHIBIT 2

POWER OF ATTORNEY

KNOWN ALL MEN BY THESE PRESENTS, that the undersigned hereby constitutes and appoints CRAIG L. SLUTZKIN as his true and lawful attorney-in-fact and agent for him and in his name, place and stead, in any and all capacities, to sign any and all documents relating to any and all Securities and Exchange Commission filings which may be required, granting unto said attorney-in-fact and agent full power and authority to do and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully to all intents and purposes as he might or could do in person, thereby ratifying and confirming all that said attorney-in-fact may lawfully do or cause to be done by virtue hereof.

This power shall continue in effect until terminated in writing.

Dated: October 5, 2005

POWER OF ATTORNEY

KNOWN ALL MEN BY THESE PRESENTS, that the undersigned hereby constitutes and appoints CRAIG L. SLUTZKIN as his/her true and lawful attorney-in-fact and agent for him/her and in his/her name, place and stead, in any and all capacities, to sign any and all documents relating to any and all Securities and Exchange Commission filings which may be required, granting unto said attorney-in-fact and agent full power and authority to do and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully to all intents and purposes as he/she might or could do in person, thereby ratifying and confirming all that said attorney-in-fact may lawfully do or cause to be done by virtue hereof.

This power shall continue in effect until terminated in writing.

Dated: September 29, 2006

POWER OF ATTORNEY

KNOWN ALL MEN BY THESE PRESENTS, that the undersigned hereby constitutes and appoints CRAIG L. SLUTZKIN as his true and lawful attorney-in-fact and agent for him and in his name, place and stead, in any and all capacities, to sign any and all documents relating to any and all Securities and Exchange Commission filings which may be required, granting unto said attorney-in-fact and agent full power and authority to do and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully to all intents and purposes as he might or could do in person, thereby ratifying and confirming all that said attorney-in-fact may lawfully do or cause to be done by virtue hereof.

This power shall continue in effect until terminated in writing.

Dated: April 9, 2012