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): February 27, 2013

Griffin Capital Essential Asset REIT, Inc.

(Exact name of registrant as specified in its charter)

Commission File Number: 000-54377

2121 Rosecrans Avenue, Suite 3321 El Segundo, CA 90245

(Address of principal executive offices, including zip code)

3106065900

(Registrant’s telephone number, including area code)

None

(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:

On February 27, 2013, eight special purpose entities that own the properties noted below and are wholly-owned by the operating partnership of Griffin Capital Essential Asset REIT, Inc. (the “Registrant”) entered into that certain Promissory Note and various other documents (collectively, the “Loan Documents”) with Midland National Life Insurance Company (“Midland”), pursuant to which Midland provided such special purpose entities with a loan in the amount of $105.6 million (the “Midland Mortgage Loan”).

At the closing of the Midland Mortgage Loan noted in Item 1.01 above, the Registrant, through the special purpose entities, drew the entire $105.6 million in funds available and utilized such funds to refinance eight of the Registrant’s properties previously serving as security for the Registrant’s credit facility with KeyBank National Association and other lenders. The Midland Mortgage Loan is secured by cross-collateralized and cross-defaulted first mortgage liens or first lien deeds of trust on the Renfro, Quad/Graphics, ITT, Westinghouse, AT&T, Travelers, Zeller Plastik, and Health Net properties (collectively, the “Secured Properties”). The documents relating to the first mortgage liens or deeds of trust on the Secured Properties are substantially similar related to each property, and the Open-End Mortgage and Security Agreement for the Westinghouse property is attached hereto as Exhibit 10.2. The Registrant paid a loan origination fee, as well as certain other fees and expense reimbursement amounts, of $280,500 in connection with the Midland Mortgage Loan.

The Midland Mortgage Loan has a term of 10 years, maturing on April 1, 2023. The Midland Mortgage Loan requires monthly payments of interest only for the first four years and fixed monthly payments of principal and interest thereafter, with the balance due upon maturity of the loan. The Midland Mortgage Loan bears interest at a fixed rate of 3.94%. The Midland Mortgage Loan may be prepaid only in full and only after the end of the second year of the loan term, subject to 30 days’ prior notice to Midland and payment of a prepayment penalty in addition to all unpaid principal and accrued interest.

The Midland Mortgage Loan contains a number of customary representations, warranties, covenants and indemnities, including, but not limited to, a debt service coverage ratio of 1.6 times and a loan to value ratio of 60%, each as defined in the Loan Documents. In addition, pursuant to that certain Separate Guaranty of Retained Liability Matters, the Registrant, as the guarantor of the Midland Mortgage Loan, must maintain a minimum net worth of $75 million.

The Loan Documents also contain the following salient requirements (terms used below are as defined in the Loan Documents):

After the end of the second year of the loan term, the mortgagor may request a release of any of the Secured Properties, subject to the payment of certain fees and satisfaction of the terms and conditions contained in the Loan Documents, including the requirement that the debt service coverage ratio for the remaining Secured Properties must be at least 1.6 times, the loan to value ratio for the remaining Secured Properties must be at least 60%, and no more than 50% of the Secured Properties shall be released. The mortgagor may obtain a release of any of the Secured Properties by substituting another property therefor, subject to the terms and conditions contained in the Loan Documents, including the requirement that the debt service coverage ratio for the Secured Properties in the aggregate and for the substitute property individually shall each equal or exceed 1.6 times.

This description of the Midland Mortgage Loan is qualified in its entirety by the Promissory Note, Open-End Mortgage and Security Agreement for the Westinghouse Property, and Guaranty, which are attached as exhibits hereto.

On March 5, 2013, the Registrant issued a press release disclosing the entry into the Midland Mortgage Loan described above in Items 1.01 and 2.03. A copy of the press release is filed as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein solely for purposes of this Item 7.01 disclosure.

Pursuant to the rules and regulations of the Securities and Exchange Commission, the information in this Item 7.01 disclosure, including Exhibit 99.1 and information set forth therein, is deemed to have been furnished and shall not be deemed to be “filed” under the Securities Exchange Act of 1934.

(d) Exhibits.

Signature(s)

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.