The rest of his career, which lasted from 1971 to 1987, was spent in the Finnish SM-liiga. Internationally Lehtonen played for the Finnish national team at the 1977, 1979 and 1981 World Championships, as well as at junior tournaments.
Lehtonen's career from 1971 to 1987 was entirely dedicated to the Finnish SM-liiga. He also represented Finland in international hockey competitions like the World Championships of 1977, 1979, and 1981, as well as junior tournaments.