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

November 9, 2011

Date of Report (Date of earliest event reported)

ATMOS ENERGY CORPORATION

(Exact Name of Registrant as Specified in its Charter)

(972) 934-9227

(Registrant’s Telephone Number, Including Area Code)

Not Applicable

(Former Name or Former Address, if Changed Since Last Report)

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:

As reported in its news release issued November 15, 2011, Atmos Energy Corporation (“Atmos Energy”) has appointed Marvin L. Sweetin, currently vice president, customer service of Atmos Energy, as senior vice president of utility operations, effective November 9, 2011. Having served in his current position at Atmos Energy since November 2010, Mr. Sweetin, 48, will be responsible for numerous areas in his new position at Atmos Energy, including the supervision of the operations of Atmos Energy’s six utility divisions in 12 states, as well as continued responsibility for the company’s customer service, safety and training functions. Prior to his service as vice president, customer service, Mr. Sweetin served as director, technical training and director, procurement since he joined Atmos Energy in May 2000.

Although Atmos Energy is not a party to any employment agreement with Mr. Sweetin, he will receive an annual salary of $330,000 and will be eligible to participate in all other applicable incentive, benefit and deferred compensation plans offered by the company to its senior officers. Atmos Energy will also enter into a change in control severance agreement with Mr. Sweetin to provide certain severance benefits to him in the event of the termination of his employment within three years following a change in control of the company. The agreement will provide that in the case of such termination of employment, the company will pay Mr. Sweetin a lump sum severance payment equal to 2.5 times his total compensation, comprised of his annual base salary and “average bonus,” as such term is defined in the agreement. In addition, Mr. Sweetin will receive all medical, dental, vision, and any other health benefits which qualify for continuation coverage under Internal Revenue Code Section 4980B ( “COBRA coverage”), for a period of 18 months from the date of his termination. Finally, the company will pay Mr. Sweetin a lump sum payment generally equal to the actuarially equivalent of (a) an additional three (3) years of credits under our Pension Account Plan; (b) an additional three (3) years of company matching contributions under our Retirement Savings Plan and (c) the cost to the company of providing COBRA coverage benefits to Mr. Sweetin for an additional 18-month period.

However, if Mr. Sweetin is terminated by the company for “cause” (as defined in the agreement), or if his employment is terminated by retirement, death, or disability, the agreement will provide that the company will not be obligated to pay the severance benefits to Mr. Sweetin. The agreement will further provide that if Mr. Sweetin voluntarily terminates his employment except for “constructive termination” (as defined in the agreement), the company will not be obligated to pay him the severance benefits. A form of such change in control severance agreement has been previously filed with the Commission as Exhibit 10.7(a) to Form 10-K for the fiscal year ended September 30, 2010.

A copy of a news release issued on November 15, 2011 announcing this management change is filed herewith as Exhibit 99.1.

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SIGNATURE

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.

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INDEX TO EXHIBITS

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