Rettenegger, who competes for the TSU St. Veit , made his international debut at the Nordic Ski Games of the OPA 2015 in Seefeld , where he won the bronze medal in the student competition. In the following years he regularly took part in competitions in the Alpine Cup. In spring 2018, Rettenegger was the Austrian youth state champion in the team sprint in Saalfelden . He made his debut in the Continental Cup in January 2018 in Rena , where he directly reached the points. Rettenegger also won points straight away in his Grand Prix debut in Villach in summer 2018 . Rettenegger started the winter with a victory in the Alpencup, before he competed in the Continental Cup and achieved his first top 10 results. In the overall ranking of the second highest competition series, he came in 26th.
In the winter of 2019/20, Rettenegger faced international competition in various competition formats, from the Alpine Cup to the World Cup. Most often he was used in the Continental Cup , where he was consistently in the points. At the end of December 2020, he started in the World Cup for the first time as part of the national group in Ramsau , but missed his first point wins with places 35 and 37. At the end of February 2020, Rettenegger reached the podium in the Continental Cup for the first time when he and Sigrun Kleinrath , Lisa Hirner and Stefan Rettenegger finished the first mixed team competition in Eisenerz in second place behind Norway. He was then appointed to the Austrian team for the Nordic Junior World Ski Championships 2020 in Oberwiesenthal .
Personal
His brother Stefan (* 2002) is also active as a Nordic combined athlete. Rettenegger attended the HIB Saalfelden ski school. In 2020 he was accepted into the Army Sports Center.