Ordered to active duty on the carrier USS Hornet on 17 November 1941, he was appointed Lieutenant (junior grade) (temporary).

The ship launched on 25 September 1943 by the Bethlehem Steel Co.'s Fore River Shipyard, Quincy, Massachusetts; sponsored by Mrs. Pearl M. Gillette, the namesake's mother; and commissioned on 27 October 1943.

After shakedown off Bermuda, Gillette sailed from Boston on 2 January 1944 for Balboa, C.Z., where for four months she conducted intensive exercises with submarines and escorted a convoy to Guantanamo Bay, Cuba, and returned.

She sailed 9 May for Puerto Limon, Costa Rica, on a good-will tour and visited Barranquilla, Colombia, as well before returning to Boston 2 June.

From 4 July 1944 to 18 February 1945, Gillette made four round trip transatlantic escort voyages – three out of Hampton Roads and one from New York – to Oran and United Kingdom ports protecting Allied shipping.