[1][5] Shortly after he was born, his family moved to Sajaniemi in the municipality of Loppi where his father worked as a state employed gamekeeper.

[5] Mikkola first became involved in motorcycling through his childhood friend Martti Pesonen, who later competed internationally in Grand Prix road racing.

[6] At the 1967 250cc Finnish Grand Prix, Mikkola finished in an impressive sixth place against a field of top rated competitors.

[6][17] After his impressive finish at the 1968 Swedish Grand Prix, he began to receive support from the Husqvarna factory in the form of spare parts at discounted prices.

[11] Despite the support from the Husqvarna factory, he still had to serve as his own mechanic and drive his own van to races throughout Europe along with his wife and young daughter.

[22][23] His impressive performance at the end of the 1970 seasoned earned him a contract to join the Husqvarna factory team which, enabled him to quit his job as a truck mechanic to focus entirely on his racing career.

[26] Mikkola moved up to the premier 500cc class in 1972 as Bengt Aberg's teammate and won the Swiss and Czechoslovakian Grand Prix races.

[27] He finished the championship in third place behind Roger De Coster and Paul Friedrichs despite Aberg receiving preferential treatment from the Husqvarna team.

[3][33] Mikkola credited much of his success to his Husqvarna factory mechanic, Per-Olaf Persson, whose meticulous preparation and maintenance greatly improved the reliability of his motorcycle.

[32][34] Mikkola missed the German Grand Prix due to injuries suffered in practice, allowing De Coster to narrow his lead in the championship to 10 points going into the final two events of the season, meaning that De Coster would have to win three of the last four motos to secure his fourth consecutive 500cc world championship.

[32] The setting of the Belgian Grand Prix was a rugged, narrow track in the forests surrounding the picturesque hilltop Citadel of Namur.

[32] When Wolsink's engine seized, the two series points leaders once again found themselves first and second with Mikkola holding on to the lead to the end of the race.

[32] De Coster continued to widen his lead to win the second moto to extend the championship points battle to the final race of the season in Luxembourg.

[32][36][37] De Coster was magnanimous in defeat, waiting for Mikkola to return to the pits to celebrate his victory with a bottle of champagne.

[1][20][38] Mikkola was injured in a pre-season accident and then, his Husqvarna suffered suspension problems during the season, allowing De Coster to reclaim the world championship with 12 moto victories.

After a season long battle with KTM rider Guennady Moisseev, Mikkola was able to prevail by a narrow one point margin to claim the world championship.

[1] At the 1978 Motocross des Nations in Gaildorf, West Germany, Mikkola had the rare opportunity to compete against American rider, Bob Hannah, who was then near the peak of his racing career.

[42] Mikkola suffered torn ligaments in his leg during pre-season practice and, the injury continued to affect his results during the 1979 season.