The men's long jump event was part of the track and field athletics programme at the 1948 Summer Olympics. The competition was held on July 31, 1948. Twenty-one athletes from 17 nations competed. The maximum number of athletes per nation had been set at 3 since the 1930 Olympic Congress. The final was won by 27cm by American Willie Steele. It was the United States' fifth consecutive and tenth overall gold medal in the men's long jump. Theo Bruce won Australia's first long jump medal with his silver.

Argentina at the 1948 Summer Olympics in London, England was the nation's eighth appearance out of eleven editions of the Summer Olympic Games. Argentina sent to the 1948 Summer Olympics its fifth national team, under the auspices of the Argentine Olympic Committee of 199 athletes who competed in 101 events in 16 sports. It would not be until the 2016 Summer Olympics that the athlete delegation were surpassed. The medals haul of 3 golds, 3 silvers, and a bronze tied the medals haul in 1928. The achievement of 7 medals in an edition of the Olympics has yet to be matched.