The Ivory Coast international spent last season on loan at Olympique Marseille, playing in 17 league games as they finished third.

The 29-year-old centreback made over 100 appearances for United since joining from Villarreal in 2016 but his playing time was limited in recent seasons as he struggled with injuries.

Bailly, who has 49 international caps, was part of the United team that won the Europa League in the 2016-2017 season and finished runner-up in 2020-21.

Besiktas, who finished third in the Super Lig last season, are fourth in the standings this year after three games.