| Birth Date: | 15 January 1935 |
| Birth Place: | Groningen, the Netherlands |
| Death Place: | Scheveningen, the Netherlands |
| Club: | VZN, Groningen |
| Show-Medals: | yes |
Koosje van Voorn, (15 January 1935 – 5 August 2018) was a freestyle swimmer from the Netherlands. She competed in the 100 m and 4 × 100 m relay events at the 1952 Summer Olympics and won a silver medal in the relay, alongside Marie-Louise Linssen-Vaessen, Irma Heijting-Schuhmacher and Hannie Termeulen.[1]