At the 2017 Junior World Orienteering Championships, he won a bronze medal in sprint.

[3] His achievements at the 2019 Orienteering World Cup include a victory in the middle distance and a second place in knockout sprint in Laufen, Switzerland, and a second place in the middle distance at the world cup final in China.

[2] Hadorn won a silver medal in the middle distance at the 2023 World Orienteering Championships held in Switzerland, and was also part of the Swiss relay team winning the gold medals.

[4][5] Competing at the 2024 World Orienteering Championships in Edinburgh, he ran the third leg for Switzerland in the mixed sprint relay, and won the gold medal with the Swiss team, which also included Natalia Gemperle, Riccardo Rancan and Simona Aebersold.

[6][7] He also qualified for the final in the knockout sprint at the world championships, where he placed fourth, 0.2 seconds from the bronze medal.