Guadalajara defeated Toronto FC in the final to win their second CONCACAF club title and their first in the Champions League era, and qualified as the CONCACAF representative at the 2018 FIFA Club World Cup in the United Arab Emirates.
For the United States, four teams qualified for the CONCACAF Champions League, three through the Major League Soccer (MLS) season and one through its domestic cup competition: If there was any team 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, the vacated berth was reallocated to the U.S.-based team with the best MLS regular season record not yet qualified.
In line with the launch of the new format, which placed the Canadian representative directly in the CONCACAF Champions League beginning in early 2018, the Canadian Soccer Association announced in March 2017 that a special one-match playoff between the 2016 champions Toronto FC and the 2017 champions would be played on 9 August 2017 in Toronto to determine who would qualify for the 2018 CONCACAF Champions League, except in the case that Toronto FC won the 2017 edition, in which the playoff would be unnecessary and Toronto FC would qualify automatically.
[4] As Toronto FC did later win the 2017 Canadian Championship, the playoff was not played.
The five berths for the Central American Football Union (UNCAF) were allocated to five of the seven UNCAF member associations as follows: one berth for each of Costa Rica, El Salvador, Guatemala, Honduras, and Panama.
As all of the leagues of Central America employed a split season with two tournaments in one season, the champions with the better aggregate record (or any team which were champions of both tournaments) in the leagues of Costa Rica, El Salvador, Guatemala, Honduras, and Panama qualified for the CONCACAF Champions League.
[5] The sole berth for the Caribbean Football Union (CFU) was allocated via the Caribbean Club Championship, a subcontinental tournament open to the clubs of all 31 CFU member associations.
To qualify for the Caribbean Club Championship, teams had to finish as the champions or runners-up of their respective association's league in the previous season, but professional teams could also be selected by their associations if they played in the league of another country.
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 draw for the 2018 CONCACAF Champions League was held on 18 December 2017, 19:00 EST (UTC−5), at the Univision Studios in Miami, Florida, United States,[11][12] and was streamed on YouTube.
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.
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.
Winner SF2), the finalist which had the better performance in previous rounds hosted the second leg.