"Toowoomba" entered operational service immediately on commissioning. She was initially based in Sydney, and was tasked with convoy escort duties along the east coast of Australia until January 1942, when "Toowoomba" and two sister ships were ordered to Batavia. "Toowoomba" was in constant action over the next two months, and on 14 February was one of the last ships to enter Singapore Harbour before it was captured by the Japanese.