SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

(Rule 13d-101)

Under the Securities Exchange Act of 1934

Lonestar Resources US Inc.

(Name of Issuer)

Class A Common Stock, Par Value $0.001 Per Share

(Title of Class of Securities)

54240F103

(CUSIP Number)

Roland T. Kelly

11100 Santa Monica Boulevard, 11th Floor

Los Angeles, CA 90025

Tel: (310) 914-1373

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

December 22, 2016

(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 that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.  ☒

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Item 1. Security and Issuer.

This statement on Schedule 13D relates to the Class A Common Stock, par value $0.001 per share (the “Common Stock”), of Lonestar Resources US Inc., a Delaware corporation (the “Issuer”). The principal executive offices of the Issuer are located at 600 Bailey Avenue, Suite 200, Fort Worth, Texas 76107.

Item 2. Identity and Background.

This Schedule 13D is being filed by Leucadia National Corporation (“Leucadia”) on behalf of itself and its controlled subsidiaries (the “Reporting Person”). Leucadia is a diversified holding company engaged through its consolidated subsidiaries in a variety of businesses, including investment banking and capital markets, beef processing, manufacturing, oil and gas exploration and production and asset management. Leucadia also owns equity interests in businesses that are accounted for under the equity method of accounting, including a diversified holding company, real estate, commercial mortgage banking and servicing, telecommunication services in Italy, automobile dealerships and development of a gold and silver mining project.

The address of the principal office of the Reporting Person is 520 Madison Ave., New York, NY 10022. Leucadia is incorporated in the State of New York.

The names of Leucadia’s directors and executive officers (the “Scheduled Persons”) are provided on Schedule I.

During the last five years, neither the Reporting Person nor, to the knowledge of the Reporting Person, any of the Scheduled Persons, has (i) been convicted in any criminal proceeding (excluding traffic violations or similar misdemeanors) or (ii) been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction such that, as a result of such proceeding, such person was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activity subject to, federal or state securities laws or finding any violation with respect to such laws.

Item 3. Source and Amount of Funds or Other Consideration.

On December 22, 2016, the Reporting Person purchased 3,478,261 shares of Common Stock at $5.75 per share pursuant to a public offering by the Issuer. The securities were acquired by the Reporting Person using cash from working capital in the amount of approximately $20 million.

Item 4. Purpose of Transaction.

Pursuant to an Equity Commitment Letter dated August 2, 2016 between the Reporting Person and the Issuer, the Reporting Person agreed to purchase $20 million of Common Stock in any qualified offering by the Issuer completed on or before December 31, 2016. The Reporting

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Person’s agreement to purchase the Common Stock was conditioned on, amongst other things, the Issuer (i) selecting a lead underwriter approved by the Reporting Person, (ii) having, together with its subsidiaries, no more than $295 million of long-term debt outstanding (net of cash and cash equivalents), and (iii) the equity order book in the offering being no less than $40 million excluding the Reporting Person’s commitment. The Issuer agreed to pay the Reporting Person a commitment fee equal to $1 million, payable whether such an offering is launched or consummated, upon the earlier of (i) the closing of the offering, (ii) the termination of the offering and (iii) December 31, 2016. In addition, pursuant to the Equity Commitment Letter, following the Reporting Person’s acquisition of Common Stock on December 22, 2016, the Issuer is obligated to use commercially reasonable efforts to enter into arrangements to provide the Reporting Person with the right to appoint one director to the board of directors of the Issuer, provided that such right will terminate at such time as the Reporting Person and its affiliates own a number of shares of Common Stock equal to less than 50% of the shares purchased by the Reporting Person on December 22, 2016.

The Reporting Person’s controlled subsidiary Juneau Energy LLC owns immediately exercisable warrants to purchase: (i) 200,000 shares of Common Stock at an exercise price of $5.00 per share expiring August 3, 2021; (ii) 40,000 shares of Common Stock at an exercise price of $5.00 per share expiring August 10, 2021 and (iii) 260,000 shares of Common Stock at an exercise price of $5.00 per share expiring August 15, 2021.

Other than described above, the Reporting Person does not have any plans or proposals of the type referred to in Items 4(a) through (j) of Schedule 13D. The Reporting Person, however, retains the right to change its intent and to pursue any transaction contemplated in Items 4(a) through (j) of Schedule 13D and, to the extent the Reporting Person’s affiliates operate as broker-dealers, they retain the right to pursue a role as a financial advisor, underwriter or placement agent with respect to any such transaction involving the Issuer and its affiliates.

Item 5. Interest in Securities of the Issuer.

As of the date hereof, the Reporting Person is the beneficial owner of 4,478,261 shares of Common Stock representing 20.1% of the Issuer’s outstanding shares. This number includes 500,000 shares of Common Stock underlying immediately exercisable warrants to purchase Common Stock held by the Reporting Person’s controlled subsidiary Juneau Energy LLC. The Reporting Person has sole power to vote and to dispose of 3,478,261 shares of Common Stock and shared power with its controlled subsidiary Juneau Energy LLC to vote and to dispose of 1,000,227 shares of Common Stock.

Number of shares as to which such person has:

Sole power to vote or to direct the vote: 3,478,261

Shared power to vote or to direct the vote: 1,000,227

Sole power to dispose or to direct the disposition of: 3,478,261

Shared power to dispose or to direct the disposition of: 1,000,227

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Except as set forth in Item 3, the Reporting Person has not engaged in any transactions in Common Stock of the Issuer during the past 60 days.

Except as set forth in this Item 5, no person other than each respective record owner of the securities referred to herein is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities.

Item 6. Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer.

As described in Item 4, the Issuer is obligated to use commercially reasonable efforts to enter into arrangements to provide the Reporting Person with the right to appoint one director to the board of directors of the Issuer.

As described in Item 4, the Issuer agreed to pay the Reporting Person a commitment fee equal to $1 million, payable upon the closing of the December 22, 2016 offering of Common Stock.

As described in Item 4, the Issuer’s controlled subsidiary Juneau Energy LLC owns warrants to purchase an aggregate of 500,000 shares of Common Stock at an exercise price of $5.00 per share.

The Reporting Person is a party to a Registration Rights Agreement with the Issuer dated as of August 2, 2016. Pursuant to the Registration Rights Agreement, the Issuer has agreed to register for resale certain shares of Common Stock issued or issuable to the Reporting Person, including those issuable upon exercise of the warrants.

Item 7. Material to be Filed as Exhibits.

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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.

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SCHEDULE I

DIRECTORS AND EXECUTIVE OFFICERS OF THE REPORTING PERSON

The following information is provided for each of the directors and executive officers of the Reporting Persons:

Exhibit 99.1

Execution Version

August 2, 2016

Equity Commitment Letter

Ladies and Gentlemen:

Reference is made to the Securities Purchase Agreement, dated as of the date hereof (as the same may be amended, supplemented or otherwise modified from time to time, the “Purchase Agreement”), by and among, inter alia, LONESTAR RESOURCES AMERICA INC., a Delaware corporation (the “Company”), LONESTAR RESOURCES US INC., a Delaware corporation (the “Parent Company”, and together with the Company, the “Lonestar Parties”), JUNEAU ENERGY, LLC, a Delaware limited liability company, and LEUCADIA NATIONAL CORPORATION, a Delaware corporation (or its designee, the “Purchaser”). Capitalized terms used and not otherwise defined herein have the meanings ascribed to them in the Purchase Agreement.

1. Subject to and upon the terms and conditions set forth herein, the Purchaser hereby agrees that it will purchase, in a Qualified Equity Offering, a number of shares of the Parent Company’s Class A Voting Common Stock, par value $0.001 per share (“Common Stock”), equal to (a) $20,000,000 (or such lesser amount as the Parent Company may request) (the “Commitment Amount”) divided by (b) the offering price to investors in such Qualified Equity Offering less any underwriters’ discount, commissions, structuring fees or placement agent’s fees. A “Qualified Equity Offering” is an offering and sale of Common Stock by Parent Company, (i) pursuant to an effective registration statement filed with the Securities and Exchange Commission (the “SEC”) or conducted privately in reliance upon an exemption from registration under the Securities Act of 1933, as amended (the “Securities Act”); (ii) for which each of the Conditions to Closing shall have been met; (iii) the net proceeds of which are used to repay loans outstanding under the First Lien Facility and for other general corporate purposes; and (iv) which is completed on or before December 31, 2016 (the “Outside Date”). The “Conditions to Closing” include: (a) the Parent Company has selected a lead underwriter approved by the Purchaser (such approval not to be unreasonably withheld, conditioned or delayed); (b) the Parent Company and its subsidiaries having no more than $295,000,000 of long-term debt then outstanding (net of cash and cash equivalents), as defined under U.S. generally accepted accounting principles; (c) the Common Stock is listed for trading on NASDAQ; (d) the equity order book in such offering has bona fide orders totaling at least $40,000,000 (excluding, for the avoidance of doubt, the Commitment Amount); and (e) there is not then existing a Default or Event of Default.

2. In consideration of the commitment of the Purchaser hereunder, regardless of whether a Qualified Equity Offering is launched or consummated, the Lonestar Parties will pay the Purchaser a fee equal to $1,000,000 (the “Fee”), which Fee shall be payable upon the earlier of (a) the closing of a Qualified Equity Offering, (b) the termination of a Qualified Equity Offering and (c) the Outside Date. The Fee shall be paid without setoff or recoupment and shall be paid free and clear of, and without deduction or withholding for, any taxes, levies, imposts, deductions, charges, or withholdings. The Lonestar Parties and the Purchaser agree to treat the Fee for U.S. federal income tax purposes as a premium for an option to put Common Stock to the Purchaser pursuant to Section 1. The Lonestar Parties further agree to reimburse the Purchaser for all actual and documented out-of-pocket expenses, including but not limited to attorney fees and expenses, incurred by it in connection with a Qualified Equity Offering.

3. In the event the Purchaser purchases not less than the Commitment Amount in a Qualified Equity Offering pursuant to Section 1 (and as a condition to the Purchaser’s obligation to purchase the Commitment Amount pursuant to Section 1), the Lonestar Parties hereby covenant and agree that the Lonestar Parties shall use commercially reasonable efforts to enter into arrangements with the Purchaser to provide that (a) the Purchaser shall have the right to appoint one director to the Board of Directors of the Parent Company at the Purchaser’s election; and (b) the director appointed by the Purchaser shall have the right to be a member of committees to the Board of Directors; provided that the Purchaser’s right to appoint a director shall terminate at such time as the Purchaser and its Affiliates own a number of shares of Common Stock equal to less than 50% of the of the shares of Common Stock purchased by the Purchaser and its Affiliates in the Qualified Equity Offering. The Lonestar Parties represent and warrant to the Purchaser that the Board of Directors have determined that the Parent Company and its stockholders are receiving substantial benefits from the entry into the this letter agreement, the Purchase Agreement and the transactions contemplated hereby and hereby, and that the terms hereof and thereof have been determined to be in the best interests of the stockholders of the Parent Company.

4. Each of the Lonestar Parties, on the one hand, and the Purchaser, on the other, represents and warrants to the other that: (a) it has the requisite capacity and authority to execute and deliver this letter agreement and to fulfill and perform its obligations hereunder; (b) the execution, delivery and performance of this letter agreement by it has been duly and validly authorized and approved by all necessary corporate action; (c) this letter agreement has been duly and validly executed and delivered by it and constitutes a legal, valid and binding agreement of it, enforceable against it in accordance with its terms; and (d) the execution, delivery and performance by it of this letter agreement do not and will not (i) violate any law; (ii) in any material respect, result in any violation of, or default (with or without notice or lapse of time, or both) under, or give rise to a right of termination, cancellation or acceleration of any obligation or to the loss of any benefit under, any material contract to which it is a party; or (iii) violate the terms of its constituent documents.

5. Notwithstanding anything that may be expressed or implied in this letter agreement or any document or instrument delivered contemporaneously herewith, the Lonestar Parties, by their acceptance of the benefits of this letter agreement, covenant, agree and acknowledge that no Person other than the Purchaser and the Lonestar Parties shall have any obligation hereunder and that they have no rights of recovery hereunder against, and no recourse hereunder or under any documents or instruments delivered contemporaneously herewith or in respect of any oral representations made or alleged to be made in connection herewith or therewith shall be had against, any former, current or future director, officer, agent, Affiliate, manager, assignee or employee of the Purchaser (or any of their successor or permitted assignees), against any former, current, or future manager, stockholder or member of the Purchaser (or any of their successors or permitted assignees) or any Affiliate thereof or against any former, current or future director, officer, agent, employee, Affiliate, assignee, stockholder, manager or member of any of the foregoing, but in each case not including Purchaser (each, but excluding for the avoidance of doubt, the Purchaser, a “Purchaser Affiliate”), whether by or through attempted piercing of the corporate veil, by or through a claim (whether in tort, contract or otherwise) by or on behalf of Purchaser against the Purchaser Affiliates, by the enforcement of any assessment or by any legal or equitable proceeding, or by virtue of any statute, regulation or other applicable law, or otherwise; it being expressly agreed and acknowledged that no personal liability whatsoever shall attach to, be imposed on, or otherwise be incurred by any Purchaser Affiliate, as such, for any obligations of the Purchaser under this letter agreement or the transactions contemplated hereby, under any documents or instruments delivered contemporaneously herewith, in respect of any oral representations made or alleged to be made in connection herewith or therewith, or for any claim (whether in tort, contract or otherwise) based on, in respect of, or by reason of, such obligations or their creation.

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6. NOTWITHSTANDING ANY OTHER TERMS OR CONDITIONS OF THIS LETTER AGREEMENT, UNDER NO CIRCUMSTANCES SHALL THE MAXIMUM LIABILITY OF THE PURCHASER, IN THE AGGREGATE AND FOR ANY REASON, INCLUDING ITS BREACH OF ANY OF ITS OBLIGATIONS SET FORTH HEREIN, EXCEED THE COMMITMENT AMOUNT, WHETHER ON ACCOUNT OF ANY CLAIM OF ACTUAL, SPECIAL, INDIRECT, CONSEQUENTIAL OR ANY OTHER FORM OF DAMAGES OR OTHERWISE. IN THE EVENT THE PURCHASER IS FOR ANY REASON FOUND TO BE LIABLE FOR ANY AMOUNTS HEREUNDER, THE PURCHASER SHALL BE ISSUED A NUMBER OF SHARES OF COMMON STOCK EQUIVALENT TO SUCH LIABILITY BASED ON THE THEN FAIR MARKET VALUE OF THE COMMON STOCK.

7. THIS LETTER AGREEMENT SHALL BE BINDING ON THE PURCHASER SOLELY TO THE BENEFIT OF THE LONESTAR PARTIES. NO PERSON OTHER THAN THE LONESTAR PARTIES, THE PURCHASER AND THE PURCHASER AFFILIATES (WHO THE PARTIES AGREE SHALL BE DEEMED THIRD PARTY BENEFICIARIES HEREUNDER) MAY BRING ANY ACTION UNDER THIS LETTER AGREEMENT. THERE IS NO EXPRESS OR IMPLIED INTENTION TO BENEFIT ANY THIRD PARTY (OTHER THAN THE PURCHASER AFFILIATES) AND NOTHING CONTAINED IN THIS LETTER AGREEMENT IS INTENDED, NOR SHALL ANYTHING HEREIN BE CONSTRUED, TO CONFER ANY RIGHTS, LEGAL OR EQUITABLE, ON ANY PERSON OR ENTITY, OTHER THAN LONESTAR PARTIES, THE PURCHASER AND THE PURCHASER AFFILIATES. THE LONESTAR PARTIES’ CREDITORS SHALL HAVE NO RIGHT TO ENFORCE THIS LETTER AGREEMENT OR TO CAUSE THE LONESTAR PARTIES TO ENFORCE THIS LETTER AGREEMENT.

8. This letter agreement (other than Section 2 and Sections 4 through 12, which shall survive indefinitely) shall terminate, at the Purchaser’s election, upon the earliest of (a) the termination of the Purchase Agreement in accordance with its terms; (b) the funding of the Commitment Amount in accordance with Section 1; (c) the Outside Date; and (d) the date that any Lonestar Party or their Affiliates asserts in any litigation or other proceeding any claim against the Purchaser or any Purchaser Affiliate (relating to this letter agreement, the Purchase Agreement or any of the transactions contemplated hereby or thereby (including in respect of any oral representations made or alleged to be made in connection therewith) other than a claim against the Purchaser for breach of its obligations hereunder. Upon any termination as referred to in this Section 8, this letter agreement and all the obligations hereunder shall terminate immediately and be of no further force or effect, and thereafter, no person shall have any recourse against the Purchaser pursuant to this letter agreement.

9. Neither this Agreement nor any right, interest or obligation hereunder may be assigned by the Lonestar Parties without the prior written consent of the Purchaser.

10. This letter agreement may not be amended or otherwise modified other than in writing by both the Lonestar Parties and the Purchaser.

11. This letter agreement may be executed in counterparts.

12. This letter agreement shall be governed by, and construed in accordance with, the laws of the State of New York. All actions arising out of or relating to this letter agreement shall be heard and determined exclusively in the state courts of New York sitting in New York County or the federal courts

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of the Southern District of New York. Each of the parties hereto (i) consents to submit itself to the personal jurisdiction of the state courts of New York sitting in New York County or the federal courts of the Southern District of New York in the event any dispute arises out of this letter agreement or any of the transactions contemplated by this letter agreement, (ii) agrees that it will not attempt to deny or defeat such personal jurisdiction or venue by motion or other request for leave from any such court, and (iii) agrees that it will not bring any action relating to this letter agreement or any of the transactions contemplated by this letter agreement in any court other than such courts sitting in New York County in the State of New York or the Southern District of New York. THE PARTIES HEREBY WAIVE TRIAL BY JURY IN ANY ACTION, SUIT, PROCEEDING OR COUNTERCLAIM BROUGHT BY EITHER OF THEM AGAINST THE OTHER IN ANY MATTERS ARISING OUT OF OR IN ANY WAY CONNECTED WITH THIS LETTER AGREEMENT.

[Remainder of page intentionally left blank]

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Signature Page to Equity Commitment Letter

Accepted and agreed to

as of the date written above:

Signature Page to Equity Commitment Letter