The men's decathlon event at the 1948 Olympic Games took place between August 5 and August 6.

The 17-year-old Bob Mathias of the United States won with a points total of 7139.

[1] The decathlon consists of ten track and field events, with a points system that awards higher scores for better results in each of the ten components.

The athletes all compete in one competition with no elimination rounds.

All times are British Summer Time (UTC+1) Prior to the competition, the existing World and Olympic records were as follows.