Vehkonen won the Finnish 125cc national championship in 1980. He moved up the world championships in 1982 and in 1985, he won the F.I.M. world championship in the 125cc class, while riding for the Cagiva factory racing team. Vehkonen moved up to the 250cc world championship where he finished in second place for four years in succession between 1987 and 1990. He retired from competition in 1993.