Jelle Geens represented Belgium at the 2016 Summer Olympics in Rio. Two years later he won a bronze medal in the mixed team relay event at the 2018 European Triathlon Championships. In 2019 Geens won the 2019 Groupe Copley World Triathlon Montreal race and earned the bronze medal at the Hamburg Wasser World Triathlon, establishing himself as one of the rising stars on the World Triathlon circuit.
- 3rd place at the 2019 Miyazaki ITU Triathlon World Cup
- 3rd place at the 2019 Hamburg Wasser World Triathlon
- 1st place at the 2019 Groupe Copley World Triathlon Montreal
- 3rd place place at the 2019 Weert ETU Triathlon European Championships
- 2nd place at the 2018 Sarasota-Bradenton ITU Triathlon World Cup
- 1st place at the 2018 Antwerp ITU Triathlon World Cup