Semion Belits-Geiman set the World 800m Freestyle record at 8:47.4, at a meet in Kharkov, Ukraine in March 1966. That same year he won gold medals in the European Championships' 1,500m and 4x200m Freestyle Relay, and silver in the 400m Freestyle.
In 1966, Belits-Geiman was ranked 3rd in the World in the 1,500 Freestyle. Swimming lead at the 1968 Olympics 4x100 Freestyle Relay he won a silver medal, along with a bronze swimming second leg of the 4x200m Freestyle Relay. He also swam a pair of individual freestyle events, 200m and 400m, but did not medal.
Belits-Geiman also competed at the 1964 Olympics in Tokyo, with his Soviet relay team finishing seventh in the 4x200m Freestyle and eighth in the 4x100m Freestyle.
A holder of 67 Soviet national freestyle records, he was named president of the Moscow Swimming Federation in 1974.