As a member of Hämeenlinnan Pallokerho, Pentti Paasonen played field hockey during the early 1950s and won national titles in 1951, 1952, and 1954, while coming in as runner-up in 1953. He was also selected to represent his country at the 1952 Helsinki Olympics, but did not see any playing time, as Finland was eliminated in round one following a 6-0 defeat against Belgium. He did, however, earn international caps in 1953 against the Netherlands and Denmark. He also played ice hockey during the 1954-1955 season, taking part in eight matches.