| Roles | Competed in Olympic Games | |
|---|---|---|
| Sex | Male | |
| Full name | Jacobus Cornelius "Ko"•Janssens | |
| Used name | Ko•Janssens | |
| Born | 20 December 1889 in Rotterdam, Zuid-Holland |  NED |
| Died | 21 August 1970 (aged 80 years 8 months 1 day) in Epe, Gelderland | NED |
| NOC | Netherlands | NED |
| Games | Discipline (Sport) / Event | NOC / Team | Pos | Medal | As | |
|---|---|---|---|---|---|---|
| 1920 Summer Olympics | Boxing | NED |
Ko Janssens | |||
| Lightweight, Men (Olympic) | =9 |
