The squadron was formed in early 1939 and saw active service in World War II as a fleet co-operation unit providing aircrews for seaplanes operating off Royal Australian Navy cruisers.

It was disbanded in late 1944, but was re-raised in 1962 and later became an Army co-operation unit, flying helicopters in support of Australian troops during the Vietnam War.

[3][4] The amphibians were used to provide their parent ships with reconnaissance, anti-submarine protection, artillery spotting and general support.

[7] The squadron deployed to Vung Tau Air Base, South Vietnam in mid-1966 as part of the 1st Australian Task Force (1 ATF) and began flying operations on 30 June 1966.

[9] Eather contends that this "exhibited a lack of awareness by the RAAF of the requirements of the ground force in South Vietnam", and it hampered Army operations to the extent that No.

[9] Alan Stephens, in the official history of the post-war RAAF, asserts however that the latter report is a myth and that squadron records indicate it operated constantly during the period of its supposed grounding between June and September 1966.

9 Squadron Iroquois flown by Flight Lieutenants Cliff Dohle and Frank Riley completed a hazardous mission to resupply D Company, 6 RAR which was heavily outnumbered and running dangerously low on ammunition.

The mission proved vital in ensuring the survival of the Australian infantry until a relief force could fight its way through from Nui Dat and was completed despite heavy rain and the risk of ground fire.

A close professional relationship was also developed with the Special Air Service which saw the squadron provide rapid and precise insertion and extraction of patrols into jungle landing zones at tree top height.

[12] While deployed to Vietnam, in 1967 the squadron was re-equipped with updated versions of the Iroquois, and was also reinforced with personnel from the RAN and the Royal New Zealand Air Force’s No.

[14] Between 1982 and 1986, the squadron contributed eight aircraft and aircrew to the Australian helicopter detachment which formed part of the Multinational Force and Observers in the Sinai Peninsula of Egypt.

[15] In 1986, the Australian Government decided to transfer all of the RAAF's battlefield helicopter capability to the Australian Army after a decision that all battlefield helicopters should be controlled directly by the Army – a decision partly based on the Vietnam experience and problems that arose during the first few months of the deployment by having No.

9 Squadron based in Vung Tau under separate command, rather than co-located with 1 ATF at Nui Dat, approximately 50 kilometres (31 mi) north.

[18] On 3 March, the Defence Minister and Chief of Air Force announced that the squadron would be reactivated in June 2023 to operate the Tritons due to enter service in 2024.