Following the withdrawal of Honda from the sport in December 2008, he was left without a drive for the 2009 season, until Ross Brawn led a management buyout of the team in February 2009, and Button suddenly found himself in a highly competitive, Mercedes-engined car.
He went on to win a record-equalling six of the first seven races of the 2009 season, securing the World Drivers' Championship at the Brazilian Grand Prix, having led on points all season; his success also helped Brawn GP to secure the World Constructors' Championship.
He is the fourth child of South African Simone Lyons and former Rallycross driver John Button, who was well known in the UK during most of the 1970s for his so-called Colorado Beetle Volkswagen, before switching to a VW Golf Mk1 in 1978.
A dip in Button's form, combined with Montoya's victory in that year's Indianapolis 500, led to Montoya being announced as his replacement midway through the season.
Williams chose not to sell Button's contract, keeping the right to recall him in 2003. Despite the worries about his inexperience, he made few mistakes during the season, the most notable coming in the Italian Grand Prix at Monza.
Button announced in September 2016 that he would be giving up his seat at the end of the 2016 season but announced that he would remain at Mc Laren as a reserve driver and ambassador of Mc Laren until 2018.
Button began karting at the age of eight and achieved early success, before progressing to car racing in the British Formula Ford Championship and the British Formula 3 Championship.
Button was heavily hyped before his first race: former driver Gerhard Berger described him as a "phenomenon"; the head of his karting team, Paul Lemmens, compared him to Ayrton Senna; and Williams's technical director Patrick Head said he was "remarkably mature and definitely a star of the future".