bandé made his professional debut for mechelen in a 2–1 belgian first division a loss to royal antwerp f.c. on 19 august 2017, and scored his team's only goal despite coming on as a late substitute. bandé became a first-team regular, scoring nine goals in his first fifteen games. amid growing interest from many clubs, including manchester united and arsenal, on 4 december 2017, bandé agreed to join ajax at the end of the 2017–18 season for a reported fee of €9.5 million. he finished the season with 27 appearances and 12 goals, though mechelen still finished bottom of the belgian first division and were relegated.