On 24 March 1943, aircraft embarked in HMS Unicorn for deck landing training in the Clyde and A/S operations around UK waters. Later HMS Unicorn was attached to the Home Fleet and carried out a sweep to the north of Norway with HMS Illustrious.

In late August 1943, Unicorn was part of Force H, provided support and air cover along with the carriers HMS Illustrious and HMS Formidable in the Salerno Allied landings on mainland Italy.

HMS Unicorn then reverted to supply and repair duties, for aircraft repair and transport, and fleet backup and support. By early 1944, HMS Unicorn was in the Far East, still doubling as operational carrier pending the delayed arrival of the HMS Victorious.

When she returned home from Australia after the war she was stuffed with food.

Laid up for several years after the war, she was reactivated for the Korean War. Between June 1950 and October 1953, HMS Unicorn filled a vital support role to the Royal Navy and Commonwealth Aircraft carriers in Korean waters and on several occassions accompanied the operational carrier to the forward area, flying her own aircraft and acting as a spare deck. On one occasion she engaged enemy positions in North Korea with her own 4inch guns, thereby becoming more closely engaged than any of the other carriers.

HMS Unicorn was sold for scrap on 15 June 1959, and was stripped at Dalmuir and hull broken up at Troon from March 1960.