Pekka Tuomisto began his hockey career in 1980 with Kärpät Oulu and played with them until 1987. With Kärpät Oulu Tuomisto won his only Finnish title in 1981. In 1987 Tuomisto joined HIFK Helsinki and played there until the end of his playing career in 1996. Internationally Tuomisto won silvers at the 1988 Winter Olympics and 1992 World Championships and bronze at the 1991 European Championships. Tuomisto also played for the Finnish 1992 Winter Olympic team, captaining the team, and the 1992 World Championships team. Tuomisto also won two bronzes at the 1995 and 1996 World Inline Hockey Championships.