Built for service during World War II, the ship was launched in June 1944, commissioned in July, and acted as a transport and as a replenishment carrier.

Roi was a Casablanca-class escort carrier, the most numerous type of aircraft carrier ever built,[1] and designed specifically to be mass-produced using prefabricated sections, in order to replace heavy early war losses in the early engagements of the Pacific War.

She was powered with two Skinner Unaflow reciprocating steam engines, which drove two shafts, providing 9,000 horsepower (6,700 kW), thus enabling her to make 19 knots (35 km/h; 22 mph).

By the end of the war, Casablanca-class carriers had been modified to carry thirty 20-mm cannons, and the amount of 40-mm guns had been doubled to sixteen, by putting them into twin mounts.

She was launched on 2 June 1944; sponsored by Mrs. William Sinton; transferred to the United States Navy and commissioned on 6 July 1944, with Captain Percy Haverly Lyon in command.

She then underwent several transport missions, first departing from San Diego on 13 August, carrying a load of 287 passengers and 71 aircraft bound for Manus Island and Espiritu Santo.

She began operations on 4 July 1945, along with fellow escort carriers Admiralty Islands, Hollandia, and Thetis Bay.

[6] Following the end of the war, Roi joined the Operation Magic Carpet fleet, which repatriated U.S. servicemen from around the Pacific.

She was struck from the Navy list on 21 May, and sold on 31 December to Zidell Machinery & Supply of Portland, Oregon for scrapping.