Brabham was a second generation Australian, born in Hurstville (near Sydney) the son of a grocer. Brabham left school at 15 to work in a garage.
During WW II he served in the Air Force. In 1946 he opened a small repair business. He also raced midget cars and in his first season won the NSW Championship and formed a partnership with Ron Tauranac.
In 1955 he made his Grand prix debut at the British Grand Prix driving a Maserati. He soon joined the Cooper Car Company team and in 1959 Brabham won the World Championship with a Coventry Climax engined Cooper. In 1960 he won the championship again with Cooper.
In 1961 he moved onto his own team with Ron Tauranac. A newly introduced engine limit in Formula One of 1500 cc did not suit Brabham and he did not win a single race with a 1500 cc car, although his first team win came in 1964 with Dan Gurney. In 1966 a new 3000 cc formula was created, Brabham in a Repco-Brabham won the championship again. In 1967 the title went to his teammate Denny Hulme. Following injuries in the 1969 season Brabham intended to retire in 1970 but finding no top drivers available he raced for one more year, retiring after the Mexico Grand Prix. After retiring he made a complete break from racing, selling his interest in the team to Tauranac and returning to Australia. He was knighted in 1979.
All three of Brabham's sons - Geoff, Gary and David - also engaged in racing careers.