She was originally built as USS Gayety (AM-239), an Admirable-class minesweeper with a similar hull to the PCE-842-class patrol craft produced during World War II.

[6] Commissioned in the US Navy as USS Gayety (AM-239) in 1945, she was assigned in the Pacific theatre of operations, specifically around the Japanese home islands providing minefield sweeping and anti-submarine warfare patrols in the Ryukyus and off Okinawa.

27 May 1945 She suffered a near-miss from a 500-pound bomb and was damaged with several casualties who were buried at Zamami shima, Okinawa, although she was quickly put back into fighting shape.

[9] In the 1990-1993 overhaul and refit program for the 6 ships of Malvar-class patrol corvettes, PS-20 Magat Salamat wasn't included; and the following year 1994, along with her sistership PS-29 Negros Occidental, both of them was planned to be discarded instead by 1995.

[5] Safe to assume, this move was caused by the Chinese incursions on the South China Sea during that time which entails the Philippines' need for more ships, with PS-20 just serving for interim.

[13] In 2021 December 10, Magat Salamat was decommissioned alongside her sister ship Miguel Malvar, in a ceremony at Naval Base Heracleo Alano.

[14] In 2021 December 28, just 15 days after her formal retirement, the Philippine News Agency reported that she will be used "as a temporary command post for the duration of the relief operations in the Dinagat Islands which were severely devastated by Typhoon Odette".