When he was young František Mašlán was a good footballer and tennis player but his main love was ice hockey. Mašlán spent most of his career with RH Brno and represented them in 319 league matches. During his time with the club he won no fewer than 11 league titles between 1955 and 1966, in addition to finishing third in 1959 and 1967. Despite his impressive domestic record, however, he only played in three matches for the Czechoslovakia national team, with two of those being at the 1960 Squaw Valley Olympics. Two years later he was part of the team that won gold at the 1962 Winter Universiade. Away from the ice Mašlán worked as a police officer who specialised in youth crime.