The OS2U was the main shipboard observation seaplane used by the United States Navy during World War II, and 1,519 of the aircraft were built.

In replacing the standard biplane observation aircraft with a more modern monoplane design, Beisel incorporated innovations making it the first production type to be assembled with spot welding, a process Vought and the Naval Aircraft Factory jointly developed to create a smooth fuselage that resisted buckling and generated less drag.

[1] Beisel's first prototype flew in 1938, powered by an air-cooled, 450 hp (340 kW) Pratt & Whitney R-985-4 Wasp Junior radial engine.

[1] For combat missions, the pilot had a 0.30 in (7.62 mm) Browning M1919 machine gun, the receiver mounted low in the right front cockpit, firing between the engine cylinder heads, while the radio operator/gunner manned another 0.30 in (7.62 mm) machine gun (or a pair) on a flexible Scarff ring mount.

[3] The first 54 Kingfishers were delivered to the U.S. Navy beginning in August 1940, and 6 had been assigned to the Pearl Harbor–based Battle Force before the end of the same year.

The United States Coast Guard received 76 OS2U-3 Kingfishers starting in 1942 and employed them in anti-submarine warfare, reconnaissance, and search and rescue roles.

[9] The OS2U was only slowly replaced in the latter stages of World War II with the introduction of the Curtiss SC Seahawk, the first examples reaching the U.S. Navy in October 1944.