2010-11: Julius Honka played for the JyP Jyvaskyla U16 team and was an assistant captain for Finland's U16 team. He scored 6 goals with 22 assists in 35 regular season games for JyP with 38 penalty minutes and in three playoff games was scoreless with 4 penalty minutes. In seven international contests for Finland he had five assists.
2011-12: Honka skated for the JyP U18 team as a 16-year-old and played for Finland's U17 team. In 35 regular season games he scored 8 goals with 7 assists and had 32 penalty minutes. Honka scored 2 goals with 5 assists and had 6 penalty minutes in 13 games for the Finland U17 squad.
2012-13: Honka joined JyP's U20 team and played for Finland's U18 team in both the 2012 Ivan Hlinka Memorial and 2013 World Junior Championship tournaments. Playing in 42 regular season games for JyP's A junior squad he scored 4 goals with 11 assists and was -4 with 47 penalty minutes. In five games at the Ivan Hlinka tournament he had 2 assists and was +2 with 4 penalty minutes. Skating for Finland's bronze medal-winning team in Sochi, he scored 1 goal with 3 assists and was +2 with 2 penalty minutes. Honka was selected by the WHL's Swift Current Broncos in the first round (34th overall) of the 2013 CHL Import Draft.
2013-14: Honka made a successful jump from Finland to North America: skating for the Swift Current in the WHL. He got off to a fast start with the Broncos — scoring 12 goals with 24 assists in his first 35 games — and was the third-leading scorer amongst WHL defensemen heading into the World Junior Championship. Honka represented Finland in the 2014 World Junior Championship and was selected for Team Orr in the 2014 CHL/NHL Top Prospects Game.