During December 1952, the F9F-6 was introduced to service, VF-32 being the first squadron to receive the type; while developed at a relatively rapid pace, the Cougar's arrival was too late for it to engage in active combat during the Korean War.

While initial production aircraft were powered by a single Pratt & Whitney J48 turbojet engine, the F9F-7 were furnished by an Allison J33 powerplant instead.

The US Navy's flight demonstration team, the Blue Angels, adopted the type in place of its Panthers.

While the Naval Reserves flew Cougars into the mid-1960s, only the TF-9J trainer model saw actual combat, having been deployed as a Forward Air Control aircraft during the Vietnam War.

Rumors that the Soviet Union had produced a swept wing fighter had circulated a year before the Mikoyan-Gurevich MiG-15 first appeared at air shows in 1949.

This was largely because the US Navy's focus at the time was defending the battle group against high speed, high altitude bombers with interceptors, as well as escorting medium-range carrier-based bombers in all weather conditions; air-to-air combat was of less interest at that time.

Nonetheless, the US Navy appreciated the importance of getting a capable carrier-based swept wing jet fighter.

The arrival of the MiG-15, which easily outclassed straight-wing fighters in the air war over North Korea, was a major factor.

[2][3][4] Development proceeded at a relatively rapid pace, in part due to Grumman's pre-existing experience of studying prospective derivatives of the Panther guiding several of their design choices.

[5] One example of this was the design team's decision to retain the center fuselage section of the Panther relatively unchanged, as studies of various alternative arrangements had been determined to have introduced center of gravity issues that in turn would have compelled substantial redesigns of other elements of the aircraft, including its propulsion.

[5] By changing as little as possible, the company was able to produce a swept wing fighter for the US Navy in mere months, rather than the years involved in delivering a clean-sheet design.

[5] Three XF9F-6 prototypes, two airworthy and one static test airframe, were rapidly produced by modifying existing Panthers straight off the production line.

Few meaningful problems were encountered during flight testing, most being quickly resolved or accepted on the basis of the perceived urgency for such an aircraft to be made available.

[5] The Cougar proved itself to be a definitive step forward; some pilots claimed the type to have superior handling at approach speeds than the preceding Panther.

[6] In a full-power vertical dive, it could break the sound barrier without experiencing buffeting or major undesirable flight characteristics.

The original roll control arrangement, a combination of unboosted ailerons and hydraulically-actuated spoilers (referred to as "flaperons"), were insufficient when operated via mechanical linkage alone without hydraulic pressure, thus were redesigned.

[12] Armament was four 20 mm (.79 in) AN/M3 cannons in the nose and provisions for two 1,000 lb (450 kg) bombs or 150 US gal (570 L) drop tanks under the wings.

[17] The aircraft were fitted with a 3-inch-deep (76 mm) false bottom under the center fuselage to help balance the plane during landings on the flex-deck made up of a lubricated rubberized fabric.

[18][20] Work on the F9F-8 began in April 1953 with three goals: lower the airplane's stall speed, improve aircraft control at high angles of attack, and increase range.

It featured an 8 in (20 cm) stretch in the fuselage and modified wings with a greater chord, an increased area (from 300 to 337 square foot (27.9 to 31.3 m2)), and a dogtooth.

[21] The airframe changes improved low-speed and high angle of attack flying, and gave more room for fuel tanks.

All four ammunition boxes were mounted above the guns, in contrast to the split location of most previous F9Fs including the Panther.

[11] Corky Meyer, who flew both the F9F Cougar and North American FJ-3 Fury, noted that compared to the latter the Cougar had a higher dive speed limit (Mach 1.2 vs Mach 1), a higher maneuvering limit of 7.5-g (compared to 6-g), and greater endurance.

Detachments of four Cougars served with US Marines Headquarters and Maintenance Squadron 11 (H&MS-11) at Da Nang and H&MS-13 at Chu Lai, where they were used for fast-Forward Air Control and the airborne command role, directing airstrikes against enemy positions in South Vietnam between 1966 and 1968.

The Blue Angels used the F9F-8 until 1957 they were replaced by the Grumman F11F-1 Tiger, although one two-seat F9F-8T was retained for press and VIP flights.

[35] One aircraft (serial 3-A-151) is on display at the Naval Aviation Museum (MUAN) at Bahía Blanca, while the other was sold to a customer in the United States and subsequently lost in an accident on 31 October 1991.