The 2018 MLS Cup Playoffs (branded as the 2018 Audi MLS Cup Playoffs for sponsorship reasons) began on October 31 and ended on December 8 with MLS Cup 2018, the 23rd league championship match for MLS. This was the 23rd version of the MLS Cup Playoffs, the tournament culminating the Major League Soccer regular season. Twelve teams, the top six of each conference, competed in the MLS Cup Playoffs.
The first round of each conference had the third-seeded team hosting the sixth seed while the fourth-seed hosted the fifth seed in a single match to determine who advanced to the Conference Semifinals. In the Conference Semifinals, the top seed played the lowest remaining seed while the second played the next-lowest. The winners advanced to the Conference Finals. Both the Conference Semifinals and Conference Finals were played as a two-legged aggregate series, with the higher-seed hosting the second leg. The winners advanced to the MLS Cup, a single match hosted by the participant with the better regular season record which was played at Mercedes-Benz Stadium in Atlanta.
Toronto FC were the defending MLS Cup champions, but failed to qualify for the playoffs. Atlanta United FC won their first MLS Cup title.
Eastern Conference
Western Conference
The top six teams from each conference advanced to the MLS Cup playoffs.
Eastern Conference
Western Conference
<section begin="Bracket"/><section end="Bracket"/>
<section begin=KR />
|- |colspan="5" bgcolor=#87CEFA align=center|Eastern Conference
|- |colspan="5" bgcolor=#FFAEB9 align=center|Western Conference
<section end=KR />
<section begin=CSF />
|- |colspan="5" bgcolor=#87CEFA|Eastern Conference
|- |colspan="5" bgcolor=#FFAEB9|Western Conference
<section end=CSF />
New York Red Bulls win 3âÂÂ1 on aggregate.
Atlanta United win 4âÂÂ1 on aggregate.
<section begin=CF />
|- |colspan="5" bgcolor=#87CEFA|Eastern Conference
|- |colspan="5" bgcolor=#FFAEB9|Western Conference
<section end=CF />
Atlanta United win 3âÂÂ1 on aggregate.
Portland Timbers win 3âÂÂ2 on aggregate.