Born and raised in Twynholm, Kirkcudbrightshire, Coulthard came from a motorsport family: his grandfather competed in the Monte Carlo Rally and his father was a kart racer. He began karting at age eleven, winning multiple Scottish championships. In 1991, driving for Paul Stewart Racing in the British Formula 3 series, he took five victories and finished second in the championship behind Rubens Barrichello, also winning the Macau Grand Prix and the Masters of Formula Three that year.
Coulthard advanced to the International Formula 3000 series in 1992, finishing ninth. In 1993 he joined Pacific Racing in F3000, taking one victory and finishing third in the series. It was during this period that he also entered the 24 Hours of Le Mans.
In 1993, Coulthard entered the 24 Hours of Le Mans alongside John Nielsen and David Brabham for the TWR Jaguar Racing team. The trio competed in the GT class, and they won that class at the end of the race. However, the car was subsequently disqualified for a technical infringement, meaning no official result was recorded for the crew.
The Le Mans entry proved to be Coulthard's sole appearance at the Circuit de la Sarthe. Later that year, his Formula One prospects accelerated when Williams hired him as an official test driver, and from 1994 onward he was exclusively committed to grand prix racing.
Coulthard made his Formula One debut with Williams in 1994, stepping in after the death of Ayrton Senna at the 1994 San Marino Grand Prix. He scored his first victory at the 1995 Portuguese Grand Prix.
For the 1996 season Coulthard moved to McLaren, where he would remain for nine years alongside Mika Häkkinen. He won twelve more Grands Prix during his time at McLaren and finished second in the 2001 World Drivers' Championship, 58 points behind champion Michael Schumacher. He received the Hawthorn Memorial Trophy four times during his McLaren years.
In 2005, Coulthard joined the newly formed Red Bull Racing team following their purchase of the Jaguar outfit. He gave Red Bull their first podium with a third-place finish at the 2006 Monaco Grand Prix. He retired from Formula One at the end of 2008, having scored 13 wins, 12 pole positions, 18 fastest laps and 62 podiums across 246 starts.
After retiring from Formula One, Coulthard continued as a development consultant for Red Bull and pursued other racing activities. Between 2010 and 2012 he competed in the Deutsche Tourenwagen Masters (DTM) for Mücke Motorsport. He also became a prominent motorsport broadcaster, initially with the BBC and later with Channel 4, covering Formula One. He participated in the Race of Champions on multiple occasions, winning the Drivers' Cup in 2014 and 2018.
In 2019, Coulthard was elected president of the British Racing Drivers' Club, the owner of Silverstone Circuit. He was appointed Member of the Order of the British Empire (MBE) in the 2010 Birthday Honours for services to motorsport.
Coulthard stands as one of the most successful British Formula One drivers of his generation, recording victories with both Williams and McLaren during the competitive late 1990s and early 2000s. His 1993 Le Mans appearance, though ultimately voided by disqualification, came at a critical juncture before his grand prix career began in earnest.