Coulthard came from a motorsport family: his grandfather competed in the Monte Carlo Rally and his father was Scottish National Karting Champion. He began karting at age eleven and progressed through junior Scottish championships before winning the British Formula Three championship's closely contested 1991 season — finishing second behind Rubens Barrichello — while also taking victories at the Macau Grand Prix and the Masters of Formula Three. He moved to Formula 3000 for 1992 and 1993, then secured a test driver role with Williams while still racing in that series.
Coulthard entered Formula One mid-1994 when Williams called on him following Ayrton Senna's death at the San Marino Grand Prix. Making his debut in Spain, he scored his first points in Canada and achieved a second-place finish in Portugal before Nigel Mansell was brought back to cover the final three races. A contract dispute saw the Formula One Contract Recognition Board rule that Coulthard must remain at Williams for 1995.
In 1995, partnering Damon Hill, Coulthard took his first Formula One victory at the Portuguese Grand Prix, leading from pole position and controlling the race. He finished the season third in the Drivers' Championship. Despite this, he was moved to McLaren for 1996.
Coulthard's nine seasons at McLaren defined his career. The team was transformed into a championship-winning operation under the technical direction of Adrian Newey, and Coulthard was central to several of the team's best years. In 1997 he won in Australia and at Monza; in 1998 he contributed to McLaren's Constructors' Championship with a win in San Marino, though a pre-race agreement with teammate Mika Häkkinen to let the leader win from the opening lap led to controversy in the opening round when Coulthard, having led, handed the win to Häkkinen.
Coulthard won five races in 1999 and 2000, including victories at the British and Belgian Grands Prix in 1999 and at Monaco and Britain in 2000. In 2001 he achieved his career-best championship result, finishing second with victories in Brazil and Austria, 58 points behind champion Michael Schumacher. He won the Hawthorn Memorial Trophy — awarded to the most successful British or Commonwealth Formula One driver — three consecutive times from 2000 to 2002.
His later years at McLaren were less successful. The arrival of Kimi Räikkönen in 2002 introduced a formidable younger teammate, and McLaren announced in late 2003 that Coulthard would not continue beyond 2004. He remained professional throughout, winning in Monaco in 2002 and in Australia in 2003.
Following the Jaguar team's acquisition by Red Bull, Coulthard joined the new squad for 2005. The Red Bull cars were initially uncompetitive, but Coulthard secured the team's first podium at Monaco in 2006, finishing third. He remained with Red Bull through 2008, when he announced his retirement before the British Grand Prix. His final points came with a third place at the Canadian Grand Prix that year. In Brazil, his last race, his car was decorated in the colours of Wings for Life, a spinal injuries charity.
Coulthard's total Formula One record comprises 13 wins, 12 pole positions, 18 fastest laps, and 62 podiums across 246 starts.
Coulthard returned to racing in the Deutsche Tourenwagen Masters series with Mücke Motorsport from 2010 to 2012, retiring from active competition after that season. He had joined the BBC as a Formula One commentator and pundit in 2008, then moved to Channel 4 in 2016 when that broadcaster took over UK terrestrial rights. He co-owns Whisper Films, the production company that produces Channel 4's Formula One coverage. In 2022 he joined the Nordic streaming service Viaplay as a commentator and analyst alongside Mika Häkkinen and Tom Kristensen.
In 2019, Coulthard was elected President of the British Racing Drivers' Club, owners of Silverstone. He also competes in the Race of Champions, winning the Drivers' Cup in 2014 and 2018. In 2010, he was appointed Member of the Order of the British Empire for services to motorsport.
Coulthard is regarded as one of the most consistent and reliable Formula One drivers of his era, delivering points and podiums at a time when McLaren and Ferrari traded dominance. His smooth driving style suited circuits with flowing corners and technical sections, and he was admired for his racecraft and professionalism. Critics occasionally pointed to a relative weakness in single-lap qualifying pace compared to his teammates. His transition into broadcasting has made him one of Formula One's most prominent media voices, and his ambassadorship for Red Bull has remained a long-term professional relationship extending well beyond his racing career.