In a statement on Twitter, Manchester United thanked him for his “immense contribution across two spells at Old Trafford”.
The Portuguese forward is to leave Manchester United with immediate effect, the club has announced.
In a statement, the club said: “Cristiano Ronaldo is to leave Manchester United by mutual agreement, with immediate effect.
“The club thanks him for his immense contribution across two spells at Old Trafford, scoring 145 goals in 346 appearances, and wishes him and his family well for the future.
“Everyone at Manchester United remains focused on continuing the team’s progress under Erik ten Hag and working together to deliver success on the pitch.”
Ronaldo added: “Following conversations with Manchester United we have mutually agreed to end our contract early.
“I love Manchester United and I love the fans, that will never ever change. However, it feels like the right time for me to seek a new challenge.
“I wish the team every success for the remainder of the season and for the future.”