Commissioned on May 24, 1944, at Quebec City, Thetford Mines arrived in Bermuda on July 12 to work up, returning to Halifax on August 16. Soon afterward assigned to EG 25, she was transferred with the group to Londonderry in November and served in U.K. waters from then until VE-Day, working out of Londonderry and for a time out of Rosyth. On March 7, 1945, she helped sink U 1302 in St. George's Channel, and on May 11 arrived in Lough Foyle as escort to eight surrendered U-boats. She returned home late in May, was paid off November 18 at Sydney and laid up at Shelburne. In 1947 she was sold to a Honduran buyer who proposed converting her into a refrigerated fruit carrier.