[2][3] Larsen took up shooting early, and was training in a city club by the age of 14.

His talent was noticed by Hans Schultz, an Olympic shooter who owned a guns workshop in Otterup.

[2] In 1912 Larsen won the bronze medal in the 300 metre free rifle, three positions event and also with the Danish team in the team free rifle competition.

He also participated in the following events:[3] Eight years later Larsen won the gold medal as member of the Danish team in the team 300 metre military rifle, standing event and the silver medal in the 300 metre free rifle, three positions competition.

He also participated in the following events:[3] In 1924 Larsen won the bronze medal in the 600 metre free rifle competition and finished sixth with the Danish team in the team free rifle event.