All 27 United States-based MLS teams will compete in the 2027 U.S. Open Cup, marking the tournament's first year with full league participation since 2023.
MLS has lifted the rule capping clubs at two non-league competitions, allowing qualified teams to feature in the U.S Open Cup, Leagues Cup and Concacaf Champions Cup in addition to the regular season.
Only 16 United States-based MLS clubs participated in the 2026 edition of the U.S. Open Cup, while 18 MLS clubs, including those based in Canada, participated in the Leagues Cup.
Clubs will enter the tournament in the round of 64 beginning in July of next year to align with the start of the new summer-to-spring MLS competition schedule for the 2027-28 regular season.
MLS clubs will also receive hosting priority for their opening match of the competition.
"The Lamar Hunt U.S. Open Cup connects all leagues, clubs and fans in a unique way," said Nelson Rodriguez, MLS executive vice president of sporting and matchday. "For MLS clubs, it's a chance to write a special chapter in the tournament's history and earn qualification to the Concacaf Champions Cup."
A live draw will then be held after the round of 64 to determine the round-of-32 and round-of-16 matches and hosting privileges.
The 2027 U.S. Open Cup round of 32 is set to be played on Sept.14 and Sept. 15, while round-of-16 dates will be confirmed at a later time. The competition will then resume for the quarterfinals on Nov. 23-24, with the semifinals on Dec. 1 and the final on Dec. 15.
The tournament will also amend certain roster rules for the upcoming edition, expanding gameday squads from 18 players to 20.
"MLS clubs may select from any contracted first-team, MLS NEXT Pro, and academy players. This flexibility helps provide younger players with competitive minutes while allowing clubs to manage multiple competitions," MLS said in a news release.
The 2026 edition of the U.S. Open Cup remains ongoing, with four MLS teams competing in the semifinals, set for Sept. 16.
The 2002 Open Cup champion Columbus Crew will host 2022 champion Orlando City SC in the first semifinal, while the Colorado Rapids host St. Louis City in the second.
The winner of the Columbus-Orlando contest will host the final on Oct. 21.