Seidl started Nordic combined in 1998 and made his international debut at FIS junior competitions in March 2007. From September 2008 he started in the Alpine Cup and achieved the points for the first time in Kranj's second competition . Seidl came into the top 10 for the first time at the Gundersen Normal Hill Alpine Cup in Seefeld in Tyrol on December 18, 2009. At the Nordic Junior World Ski Championships 2010 in Hinterzarten , Seidl achieved 12th place on the normal hill and over 5 km. The race over 10 km was able to do so he didn't quit. With his teammates he reached ninth place in the team competition. A few days later, Seidl started the Nordic Combined Continental Cup for the first time in Eisenerz and also won his first points in 24th. Back in the Alpencup he secured two fifth places in Lauscha and Chaux-Neuve in February and March.
In August 2010, Seidl started the Nordic Combined Grand Prix for the first time in Oberwiesenthal , but had no chance in both races and therefore no points. At the Nordic Junior World Ski Championships in 2011 in Otepää , Seidl managed a rather disappointing 23rd place on the normal hill and over 10 km, before placing a clear seventh place in the top 10 after jumps from the same hill over the 5 km distance. As part of the Nordic Combined Grand Prix 2011 , Seidl managed a good tenth place in Liberec and thus for the first time won a point in the Summer World Cup. He also landed in the points in Oberstdorf and finally finished the Grand Prix in 27th place overall.
After further good placements in the Continental Cup and a victory in the Alpine Cup in January 2012 in Hinterzarten , Seidl got a starting place in the Nordic Combined World Cup a few days later . In his first two competitions in Val di Fiemme , however, he just missed the points. For the 2012/13 season , Seidl got a permanent starting position in the A-team and already impressed at the season opener in Ramsau am Dachstein with a good 12th place and thus the first point win. In Almaty in February he made it into the top ten for the first time, finishing fifth and sixth. After he finished seventh in the top 10 in the last World Cup of the season in Oslo , he finished his first World Cup season on a good 24th place. In the following 2013/14 season he was unable to fully build on this success and ended up in 31st place overall. In the winter of 2014/15, too, he initially remained without a top 10 result in the individual World Cups. Only with the team was Seidl able to reach sixth place in the Team World Cup in Schonach in the Black Forest . A little later he also achieved a ninth place in Val di Fiemme. Seidl had previously achieved fourth place in the Villach Grand Prix in summer 2014.
Seidl with number 1 after jumping in Ramsau 2016
In February 2015, Seidl switched back to the Continental Cup for two weeks and was able to jump and run among the top ten in four competitions. The most successful was the Continental Cup in Klingenthal , in which, in addition to winning the first, he achieved third place in the second competition. In the 2015 Nordic Combined Grand Prix , Seidl started with a second place in the Oberwiesenthal team sprint together with his partner David Pommer . He celebrated his first victory in this series at the Grand Prix in Tschagguns . In Oberstdorf he was on the podium again and finished third.
He started the 2016/17 World Cup season with fifth and fourth place in the individual competitions in Ruka, Finland . In Lillehammer , Norway , he achieved third place in the team relay together with David Pommer, Wilhelm Denifl and Philipp Orter . He was able to confirm these achievements at the World Cup in Ramsau, where he was again able to achieve fourth place in the individual. On February 4, 2017, he achieved his first podium finish with second place at the Olympic dress rehearsal in Pyeongchang .
In the summer of 2019, Seidl initially did not start in the Grand Prix competitions, but actually wanted to take part in the last two competitions in Planica . On September 6th, the Salzburg man buckled his left knee in the second training jump from the Bloudkova Velikanka at a distance of 134.5 meters and tore the anterior cruciate ligament in his left knee. Seidl was therefore out for the entire 2019/20 season.
Austria
Ruka
Chaux-Neuve
Oberwiesenthal
Planica
