Trespasser served in a number of naval theatres, home waters, the Mediterranean and the Far East during her wartime career.

While on patrol in the Gulf of Lyon, she fired three torpedoes at a dead whale, having mistaken it for an enemy submarine.

She also attacked the German auxiliary patrol vessel Uj 6073 / Nimeth Allah, but failed to hit her.

Transferred to the Pacific Far East, she torpedoed and damaged the Japanese auxiliary gunboat Eifuku Maru off Burma.

She survived the war and continued in service with the Navy, finally being scrapped at Gateshead on 26 September 1961.