The Brabham team had been competing in partnership with engine supplier Alfa Romeo since 1976 and won races in the 1978 season. However, the team's 1979 car, the BT48, was not a great success. Alfa Romeo started entering their own Type 177 and Type 179 cars in Formula One Grands Prix that summer, helping to convince the Brabham team owner Bernie Ecclestone that the partnership was over. Motorsport author Alan Henry writes that Ecclestone did not want his team to take second place to an Alfa Romeo works team, and that the team designing Alfa Romeo's cars were drawing on Brabham knowledge.

Alfa's engines were powerful, but had proved troublesome and according to Henry, "the days during which pure power was the main criterion had temporarily vanished by the start of 1979". Instead aerodynamic ground effect, as brought to Formula One by the Lotus 78 two years earlier, was the most important factor. To allow them to focus on this, the Brabham team reverted to a known quantity, the reliable and widely-used Ford Cosworth DFV engine that it had last used in 1975. Three BT49s were designed and built in only six weeks for the Canadian Grand Prix on 30 September 1979; two of them were converted BT48 chassis and one was newly built.

The BT49's racing career got off to an unsettled start when Brabham's lead driver, Niki Lauda, abruptly quit the sport after 10 laps of the first practice session at the penultimate race of the 1979 season, the Canadian Grand Prix.

Nelson Piquet

The car soon showed promise: Piquet ran third in the race on the high speed Circuit Île Notre-Dame before retiring with a broken gearbox. Lauda's replacement, Argentine novice Ricardo Zunino, was seventh of the nine who completed the race.