The Osprey Mk IV was a navalized variant of the Hawker Hart biplane fighter. It was powered by a Rolls-Royce Kestrel II engine and armed with a single forward-firing 7.7 mm machine gun, as well as a single 7.7 mm for a gunner. The Osprey was put into service in 1932 and served until 1944 throughout WWII as both land-based and ship-based reconnaissance aircraft. Six Ospreys were also sold to Sweden where they were used on the seaplane cruiser HSwMS Gotland. The Spanish Republican Air Force bought a single example, using a Hispano-Suiza 12Xbrs engine, and Portugal bought two Osprey IIIs in 1935 with six more in 1939.

Introduced in Update "Winged Lions", the Osprey Mk IV is a reconnaissance hydroplane used on the Leander-class cruiser HMNZS Leander and County-class cruiser HMS Kent. The Osprey, although slow and very lightly armed, is quite manoeuvrable and nimble, making it perfect for its role of laying defensive smoke screens around the vessel. However, the Osprey cannot be used to engage other ships and boats due to a lack of suspended weaponry or high-calibre machine guns or cannons.