If teams are level at the end of the second leg, the away goals rule will be used in attempt to determine a winner.

The winners advance to the MLS Cup final, a single match hosted by the participant with the better regular season record.

[3] The winner of MLS Cup 2015, Portland Timbers qualified for the 2016–17 CONCACAF Champions League.

[1] The Portland Timbers won the MLS Cup by defeating the Columbus Crew SC by a score of 2–1.

The Timbers' Diego Valeri scored the fastest goal in MLS Cup history at 27 seconds after Crew goalkeeper Steve Clark, made a fundamental error after he miscontrolled his defender's back-pass; allowing Valeri to strike at the opportunity.