Montoya began kart racing at five years old, trained by his architect father Pablo who secretly remortgaged the family home to fund his son's career. He won multiple Colombian national karting championships through the late 1980s and was inspired by Ayrton Senna and Roberto Guerrero.
He moved into car racing in Colombia in 1992 before travelling to Europe, competing in the British Formula Vauxhall Lotus Championship with Paul Stewart Racing in 1995 and advancing to British Formula Three in 1996. In 1997 and 1998 he raced in International Formula 3000, finishing second in 1997 and winning the championship in 1998 for Super Nova Racing with a seven-race winning total across both seasons, including four victories in 1998.
During 1998 Montoya also served as a test driver for Williams, covering 5,000 miles and studying telemetry for the team's race drivers.
Montoya debuted in CART with Chip Ganassi Racing (CGR) in 1999 on a three-year contract and won the series championship as a rookie — the second rookie champion in CART history after Nigel Mansell. He won seven races in 1999, including three consecutive victories early in the season. In 2000, driving in the rival Indy Racing League, he entered the Indianapolis 500 and led 167 of its 200 laps to win on his first attempt, becoming the first rookie winner since Graham Hill in 1966.
Montoya joined Williams for 2001, debuting in a car capable of winning but prone to unreliability. He won his maiden race at the 2001 Italian Grand Prix from pole position — the first Formula One victory for a Colombian driver. In 2002 he qualified on pole seven times and took multiple podiums, finishing third in the World Drivers' Championship. In 2003, his strongest season, he won the Monaco Grand Prix and the German Grand Prix (the latter by over a minute from pole), finished third in the championship with 82 points, and was mathematically in title contention into the second half of the season.
In 2004 Williams ran an underperforming twin-keel chassis, but Montoya recovered to win the season-ending Brazilian Grand Prix, finishing fifth in the championship with 58 points.
Montoya signed with McLaren for 2005 alongside Kimi Räikkönen. Despite missing two early races with a hairline fracture in his left scapula (replaced by Pedro de la Rosa at Bahrain), he won three Grands Prix — Britain, Italy, and Brazil — and finished fourth in the championship with 60 points.
The 2006 season proved troubled. Montoya struggled with an understeering MP4-21 and a strained relationship with team management. He was involved in an eight-car accident on the opening lap of the United States Grand Prix and departed McLaren following that race, replaced again by de la Rosa. He ended the season eighth in the championship with 26 points.
His F1 totals: seven race wins, seven poles, and 456 points across 94 starts for Williams and McLaren.
Montoya switched to NASCAR with Chip Ganassi Racing from late 2006, viewing American racing as a better fit than the politics of Formula One. He won three Cup Series races: the 2007 Toyota/Save Mart 350 at Infineon Raceway (making him the first foreign-born NASCAR winner since Ron Fellows in 2001), the 2007 Telcel-Motorola Mexico 200 in the Nationwide Series, and the 2010 Heluva Good! Sour Cream Dips at the Glen at Watkins Glen. He qualified for the Chase for the Sprint Cup in 2009 and finished eighth in the standings, his career-best NASCAR season.
Montoya returned to IndyCar with Team Penske in 2014. He won the Pocono IndyCar 500 that year — the fastest 500-mile race in IndyCar history at 202.402 mph — and in 2015 won the Indianapolis 500 for the second time, battling Will Power in the closing laps. He narrowly lost the 2015 IndyCar championship to Scott Dixon on a tiebreak after finishing the season with the same points total.
In endurance racing, Montoya won the 24 Hours of Daytona three times (2007, 2008, and 2013) with Chip Ganassi Racing, and he and co-driver Dane Cameron won the 2019 IMSA SportsCar Championship in the Prototype class with Team Penske.
Montoya's career across CART, IndyCar, Formula One, NASCAR, and endurance racing is exceptional for its breadth and depth. He is one of fewer than five drivers to have won both a Formula One Grand Prix and the Indianapolis 500. His forthright personality and aggressive driving style made him both celebrated and controversial throughout his career. The Kartódromo Juan Pablo Montoya in Tocancipá, Colombia, is named in his honour, and he received the Lorenzo Bandini Trophy in 2002 in recognition of his breakthrough Formula One season.