The Columbus Crew completed the transfer of United States international midfielder Aidan Morris to Middlesbrough of the English Championship Friday.
He joins the English second-tier side for a reported $4 million transfer fee plus a percentage of any future sell-on fees.
Morris, 22, recorded two goals and six assists in 16 matches (15 starts) this season.
The two-time MLS Cup champion and 2023 All-Star has six goals and 14 assists in 83 MLS matches (67 starts) since making his debut with the Crew in 2020. He joined the Crew academy in 2017 and played college soccer for Indiana in 2019 and then signed with the Crew for the 2020 season.
"Watching Aidan's growth as a player and person during his time at the Crew has been a true privilege, and we greatly appreciate his dedication to the club and our city," said Crew general manager Issa Tall.
"Aidan has always been focused on learning and improving, and he's an exceptional role model for our academy players. We are proud of what Aidan accomplished individually and with our club as he made a significant impact in the Crew's history.
"He always aspired to play in Europe and earned the opportunity, and we look forward to him further displaying his form and character as he joins Middlesbrough."
Internationally, Morris has earned five caps with the USMNT and could feature at this summer's Paris Olympics.
"I'm just so blessed. ... My heart is Black & Gold. It's been an amazing ride," Morris shared after the Crew's 4-0 victory against Sporting Kansas City last weekend. "Besides all the MLS Cups, I've created amazing relationships here with amazing people, and that goes a lot more of a way than winning."
Information from Field Level Media and The Associated Press contributed to this report.