The transition was finalized on 6 March 2009. On 17 March 2009, the FIA officially approved the name change from Honda Racing F1 Team to Brawn GP. Although Brawn led the purchase of the existing Brackley factory and staff, the FIA considered Brawn GP to be an entirely new entry. FIA vice-president Keith Hayes agreed to waive the standard entry fee in recognition of the team's circumstances. During the naming process, a revival of the Tyrrell name was considered, as was the name "Pure Racing." The latter was blocked by Mercedes-Benz, as the name "Pure Racing-Mercedes" might have implied it was the Mercedes works team, a status then held by McLaren.
The team's 2009 car, the BGP 001, began development in early 2008 as the Honda RA109. Following the withdrawal of the Japanese marque, the car was modified to accommodate a Mercedes-Benz engine. According to team CEO Nick Fry, the Mercedes engine accounted for 50 percent of the team's upturn in performance, and he stated the team would not have won the championship with the original Honda engines. A key innovation of the redesigned car was the "double diffuser," a controversial aerodynamic feature that provided a significant downforce advantage. While protested by Ferrari, Red Bull Racing, and Renault, the FIA governing body declared the design legal in April 2009.
Brawn GP competed only in the 2009 season with drivers Jenson Button and Rubens Barrichello. On its racing debut at the Australian Grand Prix, the team took pole position and achieved a 1–2 finish. Button won six of the first seven races of the season. At the Brazilian Grand Prix on 18 October 2009, Button secured the Drivers' Championship, and the team clinched the Constructors' Championship.
In its single year of competition, Brawn GP won eight of the seventeen races and obtained fifteen podiums. With a total of 172 points, the team achieved an average of 10.12 points per Grand Prix (derived from 172 points over 17 races). By winning both titles in its only year of competition, Brawn GP became the only constructor with a 100% championship success rate.
The team's independent existence concluded on 16 November 2009, when it was confirmed that Daimler AG and Aabar Investments had purchased a 75.1% stake in the team for a reported £110 million. The team was rebranded as Mercedes GP for the 2010 season. In its year of operation, Brawn GP made a profit of £98.5 million, with directors including Ross Brawn and Nick Fry sharing £20 million in dividends. Ross Brawn remained as team principal of the successor Mercedes team until the end of 2013.