Zauner started as a Nordic combined athlete for the ÖSV in 1999 . In 1999/2000 he won the Austria Cup in the pupil class II and the special jumping event in Fulpmes. 2000/01 he was Austrian master among the students. In 2001/02 he was fourth in the Austria Cup for adults. In 2002/03 Zauner started for the first time in the B World Cup and in 2004/05 for the first time in the A World Cup of Nordic Combined, where he finished ninth in the competition in Sapporo . In 2006/07 he was tenth in the World Cup B overall ranking. At the Junior World Championships in 2003 in Sollefteå , he finished second in the sprint.
After the 2008/09 season, Zauner switched from Nordic combined to ski jumping. The 2009/2010 season started badly for him: at the start of the Continental Cup in Rovaniemi , he fell and suffered a broken collarbone. On January 16, 2010, Zauner made his debut in the Ski Jumping World Cup : In jumping in Sapporo , he finished ninth. He also took this place in the second World Cup competition in Sapporo the following day. A week later, Zauner took two sixth places in Zakopane. In Klingenthal he achieved fifth place. With the Austrian team he achieved third place on February 7, 2010 in jumping in Willingen and thus the first podium finish of his career. In individual competitions there are several fourth places to book.
On March 19, 2010, he set a new Styrian record in ski flying with 223 meters in Planica. After he disappointed with a 26th place at the start of the Summer Grand Prix 2010 in Hinterzarten , he achieved the first individual podium place in Courchevel with a second place (tied with Thomas Morgenstern ). On November 24, 2010, Zauner suffered a cruciate ligament tear in his left knee in the final training session of the Austrian team in Lillehammer before the World Cup opener in Kuusamo .
Zauner only returned to the international stage in December 2011. After fourth place in the individual competition on December 9, 2011 on the Čerťák large hill in Harrachov , he was able to land in second place with the Austrian team in the team competition. At the season opener of the Continental Cup on December 8th and 9th, 2012 in Almaty , Kazakhstan , where Zauner took third place twice, he complained of knee problems. A medical exam revealed a torn cruciate ligament in his right knee, which led to a failure for the rest of the season.