UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of

the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): September 18, 2014

QUEST RESOURCE HOLDING CORPORATION

(Exact Name of Registrant as Specified in Charter)

Registrant’s telephone number, including area code: (972) 464-0004

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

On September 18, 2014, we issued a press release announcing that we intend to offer and sell, subject to market and other conditions, shares of our common stock, together with warrants to purchase shares of our common stock, in an underwritten public offering (the “Offering”). Maxim Group LLC is acting as sole book-running manager for the Offering. There can be no assurance as to whether or when the Offering may be completed, or as to the actual size or terms of the Offering. A copy of the press release is attached hereto as Exhibit 99.1.

The information contained in this Item 7.01 and in Exhibit 99.1 shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Forward-Looking Statements

Except for the historical information contained herein, the matters set forth in this Item 7.01 and in Exhibit 99.1, including statements regarding our expectations with respect to the completion, timing, and size of the Offering, are forward-looking statements within the meaning of the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995. These forward-looking statements are subject to risks and uncertainties that may cause actual results to differ materially, including the risks and uncertainties associated with market conditions, the satisfaction of customary closing conditions related to the Offering, risks and uncertainties associated with our business and finances in general, and other risks detailed in our annual report on Form 10-K for the fiscal year ended December 31, 2013 and other filings with the SEC. These forward-looking statements are based on current information that may change and you are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this report. All forward-looking statements are qualified in their entirety by this cautionary statement, and we undertake no obligation to revise or update any forward-looking statement to reflect events or circumstances after the date of this report.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

EXHIBIT INDEX