At the 2015 open-country German Telemark Championships, Müller came in fifth. At the end of the 2014/15 season he was a guest at the Swiss championships and finished seventh. On November 27, 2015, he made his debut in the Telemark World Cup in Hintertux and did not finish in the classic sprint race. One day later he reached his first World Cup points with 17th place in the parallel sprint. In the further course of the season he achieved his best position of the season with ninth place in his home race in Bad Hindelang in the parallel sprint. In the overall World Cup ranking, he took 26th place, 16th place in Classic, 32nd place in Classic Sprint and 24th place in parallel sprint.