Reclassified DD-251, 14 November 1943, Belknap received the Presidential Unit Citation (US) for her service with TG 21.12 (Bogue group), 20 April-20 June 1943.

Following convoy duty along the east and Gulf coasts (February–June 1944), Belknap underwent conversion into a high speed transport (reclassified APD-34, 22 June 1944).

During 18–22 October she served as a screen ship during the Leyte invasion and during 3–11 January 1945 as a shore bombardment and beach reconnaissance vessel at the Lingayen Gulf landings.

On 11 January she trained all her guns on a Japanese kamikaze which eventually crashed into Belknap's number two stack, crippling her engines, killing 38 and wounding 49 including the UDTs on board.

In addition to her Presidential Unit Citation, Belknap received three battle stars for her World War II service.