Alonso was born to a mine shaft mechanic and amateur kart driver, Jose Luis Alonso, whose daughter Lorena showed no interest in the go-kart he had built. The three-year-old Fernando received the kart instead. The family lacked finances to buy rain tyres, so Alonso learned to race on slick tyres in wet conditions from the outset. Go-kart importer Genis Marco spotted Alonso, found sponsorship to cover costs, and mentored him into European series.
Alonso won three successive Spanish Junior Championships from 1993 to 1995, and in 1996 took the CIK-FIA Five Continents Cup at Genk. He made his car racing debut in the 1999 Euro Open by Nissan, winning the title with Campos Motorsport before progressing to International Formula 3000, where he finished fourth overall.
Alonso made his Formula One debut with Minardi in 2001, scoring no points in an uncompetitive car. He joined Renault as a test driver in 2002, working to improve the team, before being promoted to a race seat in 2003. At the Malaysian Grand Prix he set the youngest-ever pole position, and at the Hungarian Grand Prix he broke Bruce McLaren's record as the youngest race winner in Formula One history.
Alonso won his maiden championship in 2005, outduelling McLaren's Kimi Raikkonen over the course of a season governed by strict tyre regulations. He won seven Grands Prix for 133 points, becoming the first World Drivers' Champion from Spain and, at 24, the then-youngest in history. He successfully defended his title in 2006 against Ferrari's Michael Schumacher, winning the championship at the Brazilian Grand Prix when he needed only a single point.
His move to McLaren for 2007 paired him with rookie Lewis Hamilton. The season produced fierce inter-team rivalry, culminating in tensions at the Hungarian Grand Prix qualifying session and an espionage scandal involving McLaren and Ferrari's technical data. Both drivers finished on 109 points, with Hamilton placed second and Alonso third by count-back. Alonso and McLaren terminated their contract by mutual consent at the season's end.
Returning to Renault for 2008, Alonso won in Singapore and Japan, though the Singapore victory was later overshadowed by the revelation that Renault had instructed teammate Nelson Piquet Jr. to crash deliberately to trigger the safety car — a scandal known as "crashgate." Alonso himself was found not to have known of the arrangement.
Alonso signed for Ferrari in 2010, where he had his most sustained period as a consistent championship contender. He led the 2010 championship entering the Abu Dhabi finale by eight points but finished seventh in the race as Vettel won to claim the title. He lost the 2012 championship to Vettel by three points after a dramatic final race in Brazil where Vettel spun at the opening lap, recovered to sixth, and Alonso could only finish second. A third consecutive runner-up placing came in 2013.
After a winless 2014 season, Alonso returned to McLaren for 2015 to 2018 under Honda power, enduring years of chronic unreliability and lack of power. Departures from both the series and McLaren in 2018 were followed by a successful move into endurance racing, where Alonso and Toyota teammates Sebastien Buemi and Kazuki Nakajima won the FIA World Endurance Championship and the 24 Hours of Le Mans in both 2018 and 2019.
Alonso returned to Formula One with Alpine in 2021, scoring his first podium in seven years at the Qatar Grand Prix. He moved to Aston Martin for 2023, where the AMR23's strong early-season performance brought him multiple podiums, including his 100th career podium at the Saudi Arabian Grand Prix. He became the first driver to contest 400 Grands Prix at the 2024 Mexico City Grand Prix.
Alonso is widely regarded as one of the finest all-round drivers in Formula One history, praised for his ability to extract exceptional pace in all conditions and on all circuits. Martin Brundle compared Alonso's feel for grip to that of Ayrton Senna. Former teammate Giancarlo Fisichella noted Alonso's instinct for knowing when to push and when to conserve tyres. Alonso is known for his aggressive braking technique, using the braking zone to load the car on corner entry without sacrificing exit speed, allowing him to operate consistently at the edge of adhesion. His physical strength allows him to apply maximum brake force with fast response times, an approach he has described as creating a natural ABS effect.
Alonso chose the permanent car number 14 in the FIA's number-for-life system, reflecting that he won a kart world championship at age 14, on 14 July 1996, in kart number 14.
Beyond Formula One, Alonso attempted the Indianapolis 500 three times (2017, 2019, 2020), led 27 laps in 2017 before engine failure, and failed to qualify in 2019 following logistical issues. He won the 24 Hours of Daytona with Wayne Taylor Racing in 2019. His endurance success made him one of a small group of drivers to pursue the Triple Crown of Motorsport — victories at Monaco, Indianapolis and Le Mans — having won Monaco five times as of the mid-2020s.
Alonso has been credited with making Formula One a mainstream sport in Spain, where it was previously considered a fringe activity behind motorcycling and rallying. He has been inducted into the FIA Hall of Fame twice — as a Formula One champion and as a World Endurance champion — the first driver to achieve the honour on two occasions. He operates a driver management firm, A14 Management, and has been a UNICEF Goodwill Ambassador since 2005.