The Spanish forward, who has signed a three-year contract with Marseille, has expressed his desire to win the league title next season.
Vidal, who was released by Barcelona in January, said he is "happy" to join the club and is looking forward to playing under new coach Marcelo Bielsa.
"I am very happy to be here," Vidal told reporters. "I'm excited about this opportunity to play under Marcelo Bielsa and I'm also looking forward to helping the team achieve our goals."
Vidal has scored 47 goals in 122 appearances for Spain's national team, and has been linked with moves to several clubs over the past few years. However, he has yet to make an impact on the international stage.
In his first appearance for Marseille, Vidal scored a hat-trick in their 6-0 victory over Angers. He praised the team's performance, saying they were "very good" and that they deserved to win.
Vidal's arrival at Marseille will be a major boost for the club, which has struggled in recent seasons. The club has made several signings in the summer transfer window, including former Real Madrid defender Sergio Ramos and midfielder Adrien Rabiot.
Despite the challenges facing the club, Vidal believes he can help them challenge for the league title next season. "I know it won't be easy, but we have a strong squad and I believe we can do well," he said.
Overall, Vidal's signing will be seen as a positive move for Marseille, and could help the club improve their chances of winning the league title next season.