A defenseman, Přemysl Hainý begain his club career after World War II with LTC Praha and then moved to ATK Praha in 1948. In 1950 he was jailed by Czechoslovakian authorities, along with 11 other members of the Czechoslovak national team, after they were not allowed to play in the World Championships. The official reason was problems with visas, but the players gathered at the U Herclíků pub, and complained publicly about this, which brought the authorities down on them, who accused them of treason and trying to defect at the 1950 Worlds. Hainý got off lightly as some sentences were as long as 15 years. Although he had played for Czechoslovakia at the 1948 Winter Olympics and 1949 World Championships, he would never again be allowed to represent his country internationally. After his return to the ice in 1951, Hainý played with TJ Poldi SONP Kladno for one season, and then joined Tatra Smichov through 1955. He then played his final five seasons in Kladno with TJ Poldi SONP and DSO Baník.