He turned pro in 1974-75 with the Winston-Salem Polar Twins and then won the Dudley "Red" Garrett Memorial Award in 1975-76 with the Providence Reds. Holst played his first two NHL games with the Rangers in 1975-76. He played nine more games for the Rangers over the next two seasons but scored no points in any of the 11 games.
In 1978 Holst went to Austria and joined Innsbruck. He played in Austria through the 1992-93 season, suiting up for four other teams. He also played for Austria in the 1982, 1983, 1985, 1986, and the 1987 World Championships.