UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-K/A

(Amendment No. 1)

FOR THE FISCAL YEAR ENDED DECEMBER 31, 2012

OR

Commission file number: 000-52596

Dividend Capital Diversified Property Fund Inc.

(Exact name of registrant as specified in its charter)

(303) 228-2200

(Registrant’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:

Title of each class

Unclassified Shares of Common Stock, $0.01 par value

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) during the preceding 12 months (or 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

There is no established market for the Registrant’s shares of common stock. On July 12, 2012, the Registrant began publishing a daily net asset value (“NAV”), based on procedures and methodologies established by its board of directors, with an initial NAV on July 12, 2012 of $6.69 per share for each of its Class E, Class A, Class W and Class I classes of common stock. As of December 31, 2012, the daily NAV was $6.70 per share for each of its Class E, Class A, Class W and Class I classes of common stock.

There were approximately 181,515,800 outstanding shares of Class E common stock, and no outstanding shares of Class A, Class W or Class I common stock, held by non-affiliates as of June 29, 2012, the last business day of the Registrant’s most recently completed second fiscal quarter.

As of March 13, 2013, 178,903,629 shares of Class E common stock, 12,375 shares of Class A common stock, 12,375 shares of Class W common stock, and 12,375 shares of Class I common stock of the Registrant, each with a par value $0.01 per share, were outstanding.

DOCUMENTS INCORPORATED BY REFERENCE: Portions of the Registrant’s Proxy Statement for the 2013 Annual Meeting of Stockholders, which we will file no later than April 30, 2013, are incorporated by reference in Part III.

EXPLANATORY NOTE

The sole purpose of this Amendment No. 1 on Form 10-K/A (this “Amendment”) to the Annual Report on Form 10-K of Dividend Capital Diversified Property Fund Inc. that was filed with the Securities and Exchange Commission on March 19, 2013 (the “Form 10-K”) is to amend Exhibit 23.1 to correct certain inadvertent errors in the exhibit.

Pursuant to Rule 12b-15 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), this Amendment also contains new certifications pursuant to Section 302 of the Sarbanes-Oxley Act of 2002, which are filed as exhibits hereto. Because no financial statements have been included in this Amendment and this Amendment does not contain or amend any disclosure with respect to Items 307 and 308 of Regulation S-K, paragraphs 3, 4, and 5 of the certifications have been omitted. Pursuant to Rule 13a-14 of the Exchange Act, this Amendment also contains new certifications pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, which are filed as exhibits hereto.

Except as described above, no other amendments are being made to the Form 10-K. This Amendment does not modify or update in any way the financial statements or disclosures contained in the Form 10-K.

PART IV

ITEM 15. Exhibits and Financial Statement Schedules

The following exhibits are filed as part of this Amendment:

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized on March 21, 2013.