The goalkeeper arrived at Old Trafford in September 2023 with 166 career appearances and 53 clean sheets to his name, becoming Manchester United's first-ever Turkish player.

He made his Reds debut at Newport in January 2024, and played once during Euro 2024, as Turkey progressed to the quarter-finals. He was the hero in January’s Emirates FA Cup third-round victory at Arsenal in January 2025, saving penalties from Martin Odegaard and Kai Havertz. That was one of 10 appearances made by Altay during 2024/25 and he made his Premier League debut at Newcastle in April.

He played in six games early the following term, before the arrival of Senne Lammens, and was named in the Turkey squad for the 2026 World Cup.