Born in Huy, the son of a motorcycle dealer, Malherbe began racing at an early age and earned his racing licence in 1973. He rode a Zündapp to win the 1973 FIM 125cc European motocross championship, and repeated as champion in 1974. Malherbe finished the 1977 season third in the 250cc motocross world championship. By 1979 he had moved up to the 500cc class and again finished third in the world. In 1980, he captured his first 500cc world championship as a member of the Honda factory racing team. Malherbe successfully defended his title in 1981 and in 1984 he won his third 500cc world championship for Honda. Malherbe's 41 Grand Prix race victories placed him fourth on the all-time winners list.