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): July 31, 2013

Carter Validus Mission Critical REIT, Inc.

(Exact Name of Registrant as Specified in Its Charter)

4211 West Boy Scout Blvd.

Suite 500

Tampa, Florida 33607

(Address of principal executive offices)

(813) 287-0101

(Registrant’s telephone number, including area code)

N/A

(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:

The information reported in Item 2.03 of this Current Report on Form 8-K is incorporated herein by reference.

Increase in Borrowing Base Availability under KeyBank Line of Credit

As previously reported in a Current Report on Form 8-K filed on April 4, 2012, Carter Validus Mission Critical REIT, Inc. (the “Company”), through its operating partnership, Carter/Validus Operating Partnership, LP (“CVOP”), entered into a credit agreement (as amended from time to time, the “KeyBank Line of Credit Agreement”) with KeyBank National Association (“KeyBank”) and the other lenders party thereto, to obtain a secured revolving credit facility in an aggregate maximum principal amount of $110,000,000 (the “KeyBank Line of Credit”), consisting of a $55,000,000 revolving line of credit, with a maturity date of November 19, 2015, subject to CVOP’s right to a 12-month extension, and a $55,000,000 term loan, with a maturity date of November 19, 2016, subject to CVOP’s right to a 12-month extension.

On July 31, 2013, in connection with the Company’s acquisition of a 55,740 rentable square foot healthcare facility located in Fayetteville, Arkansas (the “Physicians’ Specialty Hospital”), CVOP, through a wholly-owned subsidiary, entered into a joinder agreement and an assignment of leases and rents with KeyBank to add the Physicians’ Specialty Hospital to the collateral pool of the KeyBank Line of Credit, which increased CVOP’s borrowing base availability under the KeyBank Line of Credit by approximately $13,048,000. CVOP also pledged a security interest in the Physicians’ Specialty Hospital as collateral to secure the KeyBank Line of Credit pursuant to a mortgage agreement, dated July 31, 2013.

As previously disclosed in the Current Report on Form 8-K filed on March 19, 2013, the KeyBank Line of Credit bears interest at per annum rates equal to, at CVOP’s option, either: (a) the London Interbank Offered Rate, plus an applicable margin ranging from 2.50% to 3.50%, which is determined based on the overall leverage of CVOP; or (b) a base rate which means, for any day, a fluctuating rate per annum equal to the prime rate for such day, plus an applicable margin ranging from 1.25% to 2.25%, which is determined based on the overall leverage of CVOP.

As of July 31, 2013, the total borrowing base availability under the KeyBank Line of Credit was $110,000,000. As of July 31, 2013, the outstanding balance under the KeyBank Line of Credit was $55,000,000 and the Company had approximately $55,000,000 remaining available thereunder.

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.