2010-11: Emil Aronsson played in the Djurgardens club in Sweden and appeared in five games for the club's top U16 team. He scored 2 goals with 2 assists and had 6 penalty minutes in elite league play.
2011-12: Aronsson joined the Huddinge IK U18 team as a 16-year-old. In 32 games (including two playoff games) he scored 7 goals with 14 assists and was +18 with 33 penalty minutes.
2012-13: Aronsson skated for Huddinge IK's U20 team in Sweden's SuperElit junior league. He played 35 regular season games — scoring 11 goals with 7 assists — and was -12 with 12 penalty minutes as Huddinge IK finished last in the league. In three Kval series games he was -3 with 1 assist. Aronsson was selected by Blainville-Boisbriand in the first round (45th overall) of the 2013 CHL Import Draft.
2013-14: Aronsson moved to North America to skate for Blainville-Boisbriand; one of two players from Sweden to compete in the QMJHL. Going from last-place Huddinge IK to the Armada, one of the QMJHL's top teams, he scored 10 goals with 15 assists and was +15 with 10 penalty minutes in his first 39 games; missing time in October due to injury. Aronsson was ranked 46th amongst North American skaters in Central Scouting's mid-term rankings prior to the 2014 NHL Draft.