[1] Due to the COVID-19 pandemic, the tournament, which usually starts in mid-February each year, was started in April, and concluded with the final in October, which was played as a single-leg match hosted by the finalist which had the better performances in previous rounds.

Monterrey, also from Mexico, won their fifth CONCACAF Champions League title, defeating fellow Mexican club América in the final to qualify for the 2021 FIFA Club World Cup.

For the Apertura tournament, the playoff winners and runners-up qualified, while for the Clausura tournament, no playoffs were held due to the league's suspension; the two highest ranked teams in the regular season at the time of suspension instead qualified.

For the United States, four teams qualified for the CONCACAF Champions League, two through the Major League Soccer (MLS) season and two through its domestic cup competitions: If there were any teams which qualified through multiple berths, or if there was any Canada-based MLS team which were champions of the MLS Cup, the Supporters' Shield, or conference regular season (not applicable for 2021 CONCACAF Champions League), the vacated berth was reallocated to the U.S.-based team with the best MLS regular season record not yet qualified.

For Canada, the champions of the Canadian Championship, its domestic cup competition which awarded the Voyageurs Cup, were originally set to qualify for the CONCACAF Champions League.

Teams from the Caribbean Football Union (CFU), which consisted of 31 member associations, qualified for the CONCACAF Champions League either as champions of the CONCACAF Caribbean Club Championship, the first-tier subcontinental Caribbean club tournament, or through the CONCACAF League.

[4] Another three teams from the Caribbean qualified for the CONCACAF League, which were the runners-up and third-placed team of the CONCACAF Caribbean Club Championship, and the winners of a playoff between the fourth-placed team of the CONCACAF Caribbean Club Championship and the champions of the CONCACAF Caribbean Club Shield, the second-tier subcontinental Caribbean club tournament which was open to teams from non-professional leagues, where they could qualify as champions of their respective association's league in the previous season.

In the following table, the number of appearances, last appearance, and previous best result count only those in the CONCACAF Champions League era starting from 2008–09 (not counting those in the era of the Champions' Cup from 1962 to 2008).

The CONCACAF Club Index, instead of ranking each team, was based on the on-field performance of the teams that had occupied the respective qualifying slots in the previous five editions of the CONCACAF Champions League.

To determine the total points awarded to a slot in any single edition of the CONCACAF Champions League, CONCACAF used the following formula: The slots were assigned by the following rules: The 16 teams were distributed in the pots as follows:[14] In the CONCACAF Champions League, the 16 teams played a single-elimination tournament.

In the semi-finals, the matchups were determined as follows: The semi-finalists in each tie which had the better performance in previous rounds hosted the second leg.

Winners of SF2), the finalist which had the better performances in previous rounds hosted the single-leg match.