After originally beginning his career in 1963, rallying an unlikely Volvo PV544, Mikkola would go on to win 18 WRC rallies over a long career, with his first victory coming at the 1,000 Lakes Rally in 1974 in a Ford Escort.
The first overseas driver to win the East African Safari Rally, Mikkola made his name in the British Rally Championship, culminating in a championship win in 1978 in an Escort. The following year he finished runner up in the World Championship, losing out by just a single point to Swede Björn Waldegård.
In 1980 he was runner up again in the Escort, before joining the nascent Audi operation just in time for the dawn of Group B rallying and the revolution that was the Audi Quattro. A successful partnership from the off Mikkola led his first rally for Audi at Monte Carlo, before winning his second – Rally Sweden. Although he would eventually finish third, mostly due to reliability problems for the new Audi, and then third again in 1982, the following season would be his year.