The ship, originally designated a "patrol gunboat," PG-190, was ordered by the United States Maritime Commission under a United States Navy contract as USS Hornby. She was reclassified as a "patrol frigate," PF-82, on 15 April 1943 and laid down by the Walsh-Kaiser Company at Providence, Rhode Island, on 28 August 1943. Intended for transfer to the United Kingdom, the ship was renamed Montserrat by the British prior to launching and was launched on 27 September 1943.
Transferred to the United Kingdom under Lend-Lease on 31 August 1944, the ship served in the Royal Navy as HMS Montserrat (K586) on patrol and escort duty.
The United Kingdom returned Montserrat to the U.S. Navy on 11 June 1946. She was sold to the John J. Duane Company of Quincy, Massachusetts, on 30 November 1947 for scrapping.