Commissioned on December 8, 1941, at Sorel, Fredericton arrived at Halifax on December 18. She was assigned to WLEF until July, 1942, when she joined Halifax Force (Aruba Tanker Convoys). In September, after one round trip to Aruba, she was placed under U.S. operational control to escort New York-Guantanamo convoys. She arrived in New York for the last time on February 21, 1943, rejoining WLEF in March. After a major refit at Liverpool, N.S., from June 9 to October 10, 1943, and workups at Pictou, she joined EG C-1 and for the next ten months was employed as an ocean escort. She left Londonderry on September 30, 1944, for convoy ON.256 and upon arriving in Canada, went to Saint John, N.B. for two months' refit. This was completed in mid-December and, in January, 1945, the ship proceeded to Bermuda for three weeks' workups. In February she joined EG C-9, with which she was to spend the balance of the war as ocean escort. Fredericton was paid off on July 14, 1946, at Sorel and broken up in 1946.