The Turkey international has struggled for regular football since arriving from Fenerbahçe in the summer of 2023, making just 17 appearances in total across three seasons at Old Trafford, largely as back-up to André Onana and, more recently, Senne Lammens.
Manchester United confirmed the move in an official statement, saying the 28-year-old "has agreed to join La Liga side Celta Vigo on loan for the duration of the 2026/27 season, subject to registration," adding that he made six appearances for the club last season.
Celta Vigo have confirmed the loan includes an option to make the move permanent, with reports putting the buy option at around €4m. The Spanish club will cover Bayındır's wages in full for the season, with the deal also including performance-related bonuses and a sell-on clause protecting United's future interest in the player.
Celta finished sixth in La Liga last season under head coach Claudio Giráldez and will compete in the Europa League this term, offering Bayındır the prospect of regular football and European competition after a frustrating spell in Manchester.
The goalkeeper's contract at Old Trafford runs until 2027, with the club holding an option for a further year. Bayındır is expected to travel to Italy to link up with Celta's pre-season training camp, where the club are due to play friendlies against Sassuolo and Napoli, and will compete with Romanian goalkeeper Andrei Radu for the number one shirt at the Balaídos.
United wished the 28-year-old "the best of luck for the campaign ahead" as he looks to rebuild his career and reputation under Michael Carrick, who has overseen a wider reshuffle of United's goalkeeping department this summer that has also seen Onana join Trabzonspor on loan.