Hakkinen was born on 28 September 1968 in Vantaa, Finland. He began karting at the age of five and won his first karting race in 1975. Between 1983 and 1986 he took three consecutive Formula Nordic 100cc titles, becoming a dominant figure in Scandinavian karting. He was a protege of 1982 Formula One World Champion Keke Rosberg, whose support helped shape his junior career trajectory.
In 1987, Hakkinen transitioned from karting to car racing by purchasing a Reynard Formula Ford 1600 from fellow Finn JJ Lehto. He won the Finnish, Swedish, and Nordic Formula Ford championships in that debut year. In 1988, he competed in the GM Vauxhall-Lotus Challenge, taking three victories and finishing runner-up, and won the Opel-Lotus EDFA Euroseries with four victories.
Hakkinen entered the British Formula Three Championship in 1989, driving a Reynard 893 for Dragon and finishing seventh in the standings. Despite a modest championship result, he demonstrated his quality by accepting a guest invitation to the Cellnet Formula Three SuperPrix with West Surrey Racing, a race he won from pole position. He also competed in a round of the French Formula 3 championship at Le Mans-Bugatti, finishing third.
For 1990, Hakkinen secured Marlboro sponsorship through the highly competitive Marlboro World Championship Team academy programme. The judging panel included McLaren team principal Ron Dennis, 1976 Formula One World Champion James Hunt, and Formula 3000 team bosses. Hakkinen performed strongly in his test and won the backing. He moved to West Surrey Racing — the team for which he had driven as a guest in 1989 — and converted that platform into the British Formula Three title.
Hakkinen took nine victories across the season and finished with 121 points to claim the championship, with fellow Finn Mika Salo as his nearest rival in the standings. The margin of victory and the consistency of his performances across the season marked him out as the standout driver in a competitive field.
Following his British Formula Three title, Hakkinen contested the 1990 Macau Grand Prix, one of the most prestigious Formula Three events on the international calendar. He drove to pole position and won the first heat of the event outright. In the second heat, however, he retired following a last-lap collision with Michael Schumacher. Schumacher made a mistake that closed the gap between them, and when Hakkinen moved to overtake, Schumacher changed his defensive line, resulting in contact that ended Hakkinen's race. Schumacher was classified as the overall winner.
The incident brought both drivers to wider international attention and prefigured the rivalry that would define Formula One during the late 1990s.
After winning the British Formula Three title, Hakkinen tested a Formula One car with Benetton at Silverstone, completing 90 laps and setting quicker times than regular Benetton driver Alessandro Nannini. Although Benetton did not offer him a seat, his McLaren connection through the Marlboro programme led to a contract with Lotus for 1991. He made his Formula One debut at the United States Grand Prix that year. Following two seasons at Lotus and a contract dispute resolved in McLaren's favour, he joined McLaren as a test driver in 1993, partnering Ayrton Senna for the final three rounds of the season.
Hakkinen's 1990 British Formula Three championship was the definitive confirmation of his talent after years of karting success. The West Surrey Racing partnership, which had first come together in his 1989 guest appearance, proved a natural fit, and his nine-win season remains one of the more dominant British F3 title campaigns of its era. His path from Finnish karting to British F3 champion to two-time Formula One champion, achieved largely through the Marlboro academy structure and Keke Rosberg's mentorship, became a model for how Scandinavian drivers of his generation approached the European single-seater ladder.