Formed in June 1943 at RNZAF Base Woodbourne, the squadron was initially equipped with Curtiss P-40 Kittyhawks, before converting to F4U-1 Corsair fighter bombers in 1944.

The squadron fought in the Pacific theatre during World War II, flying combat operations against Japanese forces until it was disbanded in late 1945.

The squadron deployed to Piva Airfield on Bougainville between January and March 1944 and then moved to Kukum Field on Guadalcanal in May 1944, returning to Bouganville the following month.

18 Squadron deployed from Guadalcanal to Green Island assuming responsibility for local patrols and "Dumbo" air-sea rescue escort missions from No.

[2] In January 1945, the squadron returned to Guadalcanal, before being deployed the following month in support of Australian ground troops fighting the Bougainville Campaign.