During its existence the squadron's usual composition varied depending on its operational orders.

It included a Dido-class light cruiser that served as its flagship, four to five escort carriers of the Attacker-class and Ruler-class, as well as four supporting destroyers of different classes.

During Operation Dracula the squadron also included a second cruiser of the Dido class in support of the main force.

The 21st Aircraft Carrier Squadron was established in March 1945 as part of reinforcements sent to the Indian Ocean and was assigned to the East Indies Fleet.

Its responsibility was to provide daylight air cover during the initial stages of the operation until May 1945.