The ship, originally designated a "patrol gunboat," PG-186, was ordered by the United States Maritime Commission under a United States Navy contract as USS Harland. She was reclassified as a "patrol frigate," PF-78, on 15 April 1943 and laid down by the Walsh-Kaiser Company at Providence, Rhode Island, on 15 July 1943. Intended for transfer to the United Kingdom, the ship was renamed Cayman by the British prior to launching and was launched on 6 September 1943.
Transferred to the United Kingdom under Lend-Lease on 20 January 1944, the ship served in the Royal Navy as HMS Cayman (K506) on patrol and escort duty.
The United Kingdom returned Cayman to the U.S. Navy on 23 April 1946. She was sold to the United Dock Corporation of New York, New York, on 1 July 1947 for scrapping.