2010-11: Mirco Mueller moved from his home club of Wintherthur to Kloten in the top division of Swiss junior hockey. He appeared in one game in the Elite Jr A U20 league with no points nor penalty minutes. In 32 games for Kloten's U17 team he scored 12 goals with 19 assists and had 14 penalty minutes. Mueller represented Switzerland in the 2011 Europe Youth Olympic Festival.
2011-12: Mueller appeared in the Swiss Elite League as a 16-year-old, skating in seven games and scoring his first professional goal with Kloten. In 30 games for Kloten's U20 team (including four playoff games) he scored 4 goals with 5 assists and had 10 penalty minutes. Mueller was selected by Everett (WHL) in the first round (11th overall) of the 2012 CHL Import Draft.
2012-13: Mueller played in 63 WHL games for Everett in his first season in North America and skated for Switzerland in the 2013 U18 and U20 World Junior Championship tournaments. He scored 6 goals with 25 assists and was minus-10 with 57 penalty minutes for the Silvertips. Everett made the playoffs despite finishing last in the U.S. Division with the WHL's fourth-worst record. Mueller was plus-three with 1 assist and 6 penalty minutes in six playoff games. At the U20 tournament he had 2 assists and was plus-seven with 6 penalty minutes in six games for Switzerland. In five games at the U18 tournament he had 1goal with 2 assists and was minus-one with 2 penalty minutes. Mueller was ranked ninth amongst North American skaters in Central Scouting's final rankings prior to the 2013 NHL Draft.
Another in a line of young Swiss players to achieve developmental success in the WHL in the footsteps of Luca Sbisa, Nino Neiderreiter and Sven Baertshi. Mueller covers the ice well with a large frame, but will need to add some bulk. Moves the puck well. Destined for future international playing opportunities in addition to pro hockey in North America.