Mbaye scored three goals and provided two assists in 31 games in all competitions last season as PSG successfully defended their Ligue 1 and Champions League titles.
The teenager appeared in all four of Senegal's matches at the 2026 World Cup. He scored in a 3-1 defeat by France, becoming the youngest African player to score at a men's World Cup.
Mbaye is the latest attacker to join Unai Emery's side following Alejandro Garnacho, Johan Manzambi and Nicolas Jackson.
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