The Sembawang Air Base (ICAO: WSAG) is a military airbase of the Republic of Singapore Air Force (RSAF) located at Sembawang, in the northern part of Singapore. The base motto is Swift and Resolute.

Before Singapore's independence from the United Kingdom, it was a Royal Air Force station known as RAF Sembawang as well as the Royal Navy airbase, known as Royal Naval Air Station Sembawang (or RNAS Sembawang), commissioned as HMS Simbang, to the carrier pilots of the Fleet Air Arm (attached to the Eastern Fleet based in Singapore). The pilots used it for rest and refit whenever an aircraft carrier of the Royal Navy berthed at the nearby HMNB Singapore for refuel and repairs, which also housed the largest Royal Navy dockyard east of Suez up to the time of UK forces' withdrawal from Singapore.

After the Japanese capture of Singapore during World War II, the Imperial Japanese Navy Air Service took over the two RAF stations of Sembawang and Seletar. Singapore was split into north–south spheres of control, and the Imperial Japanese Army Air Force took over RAF Tengah. It was not until September 1945 that the two airfields reverted to British control following the Japanese surrender.

RAF Sembawang was a key part of Britain's continued military presence in the Far East (along with the three other RAF bases in Singapore: RAF Changi, RAF Seletar, RAF Tengah) during the critical period of the Malayan Emergency (1948–1960), the Brunei Revolt in 1962 and the Indonesia–Malaysia confrontation (1962–1966).