Vanninen, who started for the Ounasvaaran Hiihtoseura, took second place over 18 km at the Finnish championships in 1945 and 1947. In 1946 and 1947 he won the 50 km run in Ounasvaara . In early March 1945 he came in second place over 50 km at the Lahti Ski Games . The following year he won the Lahti Ski Games over 50 km for the first time. He repeated this two years later in front of his brother Pekka Vanninen . At the 1948 Winter Olympics in St. Moritz , he won the bronze medal over 50 km.