| Roles | Competed in Olympic Games | |
|---|---|---|
| Sex | Male | |
| Full name | Karl Johan "Jonni"•Hellström | |
| Used name | Jonni•Hellström | |
| Nick/petnames | The Fighting Finn | |
| Born | 13 May 1907 in Mårtensby, Uusimaa |  FIN |
| Died | 6 November 1988 (aged 81 years 5 months 24 days) in Verdun, Québec |  CAN |
| Measurements | 170 cm | |
| Affiliations | HNS — Helsinki, Uusimaa | FIN |
| NOC | Finland | FIN |
| Games | Discipline (Sport) / Event | NOC / Team | Pos | Medal | As | |
|---|---|---|---|---|---|---|
| 1928 Summer Olympics | Boxing | FIN |
Jonni Hellström | |||
| Welterweight, Men (Olympic) | =5 |
