Søren Petersen won silver medals in both 1920 and 1924 as a heavyweight. In 1920 and 1921 he was Danish amateur champion. Immediately after the Paris Games Petersen turned professional and contested 27 bouts. Only three of his fights took place in Denmark, with most of the others in Sweden, or other European countries. He won 13, lost 10, and had three draws, with one no contest, when both fighters were disqualified. Petersen lost both his two title bouts by knockout, in 1926 for the Scandinavian heavyweight title and in 1929 for the European heavyweight title. He retired from boxing in 1932 at the age of 37 after a series of defeats. Two years later he attempted a comeback in Spain without success.