In common with many of her class, Tetrarch saw extensive service in the key naval theatres, Home waters, serving in the North Sea and off the French and Scandinavian coasts, and the Mediterranean.

Tetrarch's first success came in May 1940 when she torpedoed and sank the German submarine chaser UJ B / Treff V in the Skagerrak.

Tetrarch also carried out an unsuccessful attack on the Greek tanker Olympos.

She is presumed lost to Italian mines off Capo Granditola, Sicily, Italy in late October 1941.

[2] Norman Walton, who later became the sole survivor of the sinking of HMS Neptune had visited the ship prior to its sailing to celebrate the birthday of a member of the Tetrarch, and upon realising it had sailed, he leapt off the ship and swam back to shore.