| Birth Date: | 27 May 1910 |
| Birth Place: | Genoa, Italy |
| Death Place: | Genoa, Italy |
| Sport: | Water polo |
Mario Majoni (27 May 1910[1] – 16 August 1985) was an Italian water polo player who competed in the 1948 Summer Olympics.
He was part of the Italian team which won the gold medal. He played three matches.His name is often spelled Maioni, but most Italian sources spell it with a j.