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.