UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-K

(Mark One)

For fiscal year ended December 31, 2011

OR

For the transition period from                      to                     

Commission File Number of Issuing Entity: 333-163856-01

FIRST NATIONAL MASTER NOTE TRUST

(Exact name of Issuing Entity as specified in its charter)

Commission File Number of Depositor: 333-163856

FIRST NATIONAL FUNDING LLC

(Exact name of Depositor as specified in its charter)

FIRST NATIONAL BANK OF OMAHA

(Exact name of Sponsor as specified in its charter)

(402) 341-0500

(Issuing Entity’s telephone number, including area code)

Securities Registered Pursuant to Section 12(b) of the Act:

None

Securities Registered Pursuant to Section 12(g) of the Act:

None

Title of Each Class

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.    YES  ¨    NO  x

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.    YES  ¨    NO  x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    YES  x    NO  ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    YES  x    NO  ¨

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K (§ 229.405 of this chapter) is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form    10-K.  x

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check one):

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    YES  ¨    NO  x

State the aggregate market value of the voting and non-voting common equity held by non-affiliates computed by reference to the price at which the common equity was last sold, or the average bid and asked price of such common equity, as of the last business day of the registrant’s most recently completed second fiscal quarter.

Registrant does not have any voting or non-voting common equity held by non-affiliates as of the date of this report, has not been involved in bankruptcy proceedings during the past five years and is not a corporate registrant.

DOCUMENTS INCORPORATED BY REFERENCE

No documents have been incorporated by reference into this Form 10-K.

PART IV

Item 15. Exhibits and Financial Statement Schedules.

a) Listed below are the documents filed as part of this report:

b) The exhibits listed on the Exhibit Index are filed as part of, or incorporated by reference into, this report on Form 10-K.

c) See Item 15(a) above.

SUBSTITUTE INFORMATION PROVIDED IN ACCORDANCE WITH GENERAL INSTRUCTION J TO FORM 10-K:

Item 1112(b) of Regulation AB. Significant Obligors of Pool Assets (Financial Information).

Not applicable.

Item 1114(b)(2) of Regulation AB. Credit Enhancement and Other Support, Except for Certain Derivatives Instruments (Financial Information Regarding Significant Enhancement Providers).

Not applicable.

Item 1115(b) of Regulation AB. Certain Derivatives Instruments (Financial Information).

Not applicable.

2

In re: Payment Card Interchange Fee and Merchant Discount Antitrust Litigation

Beginning in June 2005, several retail merchants filed lawsuits in federal courts, claiming to represent a class of similarly situated merchants, and alleging that MasterCard and VISA USA, together with their members, conspired to charge retailers excessive interchange in violation of federal antitrust laws. In October 2005, these suits were consolidated in In re: Payment Card Interchange Fee and Merchant Discount Antitrust Litigation, currently pending in the United States District Court for the Eastern District of New York. The plaintiffs seek unspecified treble damages, injunctive relief, attorneys’ fees and costs.

On April 24, 2006, plaintiffs filed a first consolidated and amended complaint, naming First National Bank of Omaha (the “Bank”) and others as defendants. The plaintiffs realleged the claims in their original complaints and further claimed that defendants violated federal and California antitrust laws by combining to impose certain fees and to adopt rules and practices of VISA USA and MasterCard that the plaintiffs contend constitute unlawful restraints of trade. In July 2007, the Bank entered into judgment and loss sharing agreements (the sharing agreements) with VISA USA and certain financial institutions to apportion financial responsibilities arising from any potential adverse judgment or settlement. In 2010, the Bank entered into additional contracts among the defendants relating to the apportionment of financial responsibilities which may arise from any potential adverse judgment or settlement.

Pursuant to accounting guidance on guarantees, the fair value of this guarantee has been recorded as part of the contingent litigation accrual. The estimated fair value of the liability for this litigation was $41.6 million at December 31, 2011. This liability is subject to significant estimation risk and may materially change. Furthermore, management cannot predict with any degree of certainty how the final outcome of this litigation may impact the broader credit card industry, and in this regard, the Bank.

Other Litigation Concerning the Credit Card Industry

Other antitrust lawsuits have been filed against VISA from time to time. The Bank has not been a party to these other suits; however, the Bank is a member of the MasterCard and VISA USA associations and these suits have been covered in the sharing agreements referred to above. Each of these matters has been settled by VISA, with settlement payments being made from the escrow created by VISA’s stock offerings. The Bank has not had any direct liability with respect to such settlements.

Information required by Item 1119 of Regulation AB has been omitted from this report on Form 10-K in reliance on the Instruction to Item 1119. This information has been provided previously in Registration Statement Nos. 333-163856 and 333-163856-01, filed by First National Master Note Trust (the “Trust”) and First National Funding LLC on January 14, 2010 and declared effective on January 19, 2010.

3

Each of FNBO and The Bank of New York Mellon Trust Company, N.A. (the “Trustee”) (each, a “Servicing Participant”), has been identified by the registrant as a party participating in the servicing function during the reporting period with respect to more than 5% of the pool assets held by the Trust. Each of the Servicing Participants has completed a report on an assessment of compliance with the servicing criteria applicable to such Servicing Participant (each, a “Report on Assessment”) during the Trust’s fiscal year ending December 31, 2011, which Reports on Assessment are attached as exhibits to this Form 10-K. In addition, each of the Servicing Participants has provided an attestation report (each, an “Attestation Report”) by a registered independent public accounting firm regarding its related Report on Assessment. Each Attestation Report is attached as an exhibit to this Form 10-K. Neither the Reports on Assessment nor the Attestation Reports have identified any material instances of noncompliance with the servicing criteria applicable to the Servicing Participants.

FNBO has been identified by the registrant as a servicer during the reporting period with respect to the pool assets held by the Trust. FNBO has provided a Servicer Compliance Statement, signed by an authorized officer, and such Servicer Compliance Statement is attached as an exhibit to this Form 10-K.

4

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Issuing Entity has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

SUPPLEMENTAL INFORMATION TO BE FURNISHED WITH REPORTS

FILED PURSUANT TO SECTION 15(d) OF THE ACT BY REGISTRANTS WHICH

HAVE NOT REGISTERED SECURITIES PURSUANT TO SECTION 12 OF THE ACT.

No annual report, proxy statement, form of proxy or other proxy soliciting material has been sent to Noteholders during the period covered by this Annual Report on Form 10-K and the registrant does not intend to furnish such materials to Noteholders subsequent to the filing of this report.

EXHIBIT INDEX