Junior ice hockey is amateur-level ice hockey for 16 to 21 year-old players. National Junior teams compete annually for the IIHF World Junior Championship. The United States men's national junior ice hockey team are the defending champions from the 2025 World Junior Ice Hockey Championships.

There are four levels of Junior hockey in the Canadian Club System: Major Junior, Junior A, Junior B, and Junior C. Not all teams playing in Canadian Junior leagues are based in Canada. As of 2025^[update], there were twelve US-based teams playing in various Major Junior and Junior A leagues in Canada.

In 2023, BC Hockey announced plans to restructure its Junior framework following the departure of its only Junior A league. Its three Junior B leagues (PJHL, KIJHL and VIJHL) were re-styled as "Junior A Tier 2", with plans to promote some to "Junior A Tier 1" following an independent evaluation. It was expected that those teams promoted to "Junior A Tier 1" would eventually apply for membership in the Canadian Junior Hockey League (CJHL), an association of Junior A leagues governed by Hockey Canada and its regional branches. BC Hockey expected the evaluations to be completed during the 2024–25 season. Before the process was completed, the VIJHL announced that it would also withdraw from the Hockey Canada framework and become an independent farm league for the British Columbia Hockey League (BCHL) beginning in the 2024–25 season.

Major Junior is the highest level of Junior ice hockey in Canada. There are three Major Junior leagues that collectively make up the Canadian Hockey League (CHL):

The championship teams from each league, as well as a pre-selected host team, compete for the Memorial Cup in a round-robin tournament to determine a national champion.

Major Junior players were historically deemed ineligible to play college hockey in the United States, because they were considered to be professionals by the National Collegiate Athletic Association (NCAA). Major Junior players retain their eligibility for Canadian universities however, and all three leagues have scholarship programs for players. The NCAA changed its position and decided that CHL players were no longer ineligible as of the 2025–26 season. The decision was made after a class action was filed on behalf of a player who was declared ineligible after having played two exhibition games in the OHL when he was 16 years old.

The CHL places a cap of three 20-year-old players per team, and allows up to four 16-year-olds on each roster. While 15-year-old players were formerly permitted to play a limited number of games per season at the CHL level, they are now permitted to play only if they are deemed exceptional by Hockey Canada. As of 2024^[update], nine players have qualified under this rule: centre John Tavares in 2005, defenceman Aaron Ekblad in 2011, centre Connor McDavid in 2012, defenceman Sean Day in 2013, centre Joe Veleno in 2015, centre Shane Wright in 2019, forward Connor Bedard in 2020, forward Michael Misa in 2022, and defenceman Landon DuPont in 2024. CHL teams are currently permitted two "imports" (players from outside Canada and the US) each.

Up until 1970, the leagues that were classified as Major Junior and "Junior A" today were both part of Junior A. In 1970 they were divided into "Tier I Junior A" or "Major Junior A" and "Tier II Junior A". In 1980, the three Major Junior A leagues opted for self-control over being controlled by the branches of the Canadian Amateur Hockey Association (CAHA) and became Major Junior hockey, Tier II Junior A became the top tier of hockey in the CAHA and became Junior A hockey.^{[citation needed]}