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): September 26, 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 Credit Facility

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 facility (as amended from time to time, the “KeyBank Credit Facility 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 $225,000,000 (the “KeyBank Credit Facility”), consisting of a $170,000,000 revolving credit loan, with a maturity date of August 9, 2016, subject to CVOP’s right to a 12-month extension, and a $55,000,000 term loan, with a maturity date of August 9, 2017, subject to CVOP’s right to a 12-month extension.

On September 26, 2013, in connection with the Company’s acquisition of a 142,952 rentable square foot data center located in Waukesha, Wisconsin (the “AT&T Wisconsin Data Center”), CVOP, through a wholly-owned subsidiary, entered into a joinder agreement and a mortgage, assignment of leases and rents, security agreement and fixture filing with KeyBank to add the AT&T Wisconsin Data Center to the collateral pool of the KeyBank Credit Facility, which increased CVOP’s borrowing base availability under the KeyBank Credit Facility by approximately $23,268,000. CVOP also pledged a security interest in the AT&T Wisconsin Data Center as collateral to secure the KeyBank Credit Facility.

The actual amount of credit available under the KeyBank Credit Facility is a function of certain loan-to-cost, loan-to-value, debt yield and debt service coverage ratios contained in the KeyBank Credit Facility Agreement. As of September 26, 2013, the total borrowing base availability under the KeyBank Credit Facility was $167,718,000. As of September 26, 2013, the outstanding balance under the KeyBank Credit Facility was $55,000,000 and the Company had approximately $112,718,000 remaining available thereunder.

The material terms of the joinder agreement, the mortgage, assignments of leases and rents, security agreement and fixture filings are qualified in their entirety by the agreements attached as Exhibit 10.1 and 10.2 to this Current Report on Form 8-K and incorporated herein by reference.

(d) Exhibits

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.