The club's decision follows last week's explosive interview with Piers Morgan during which Ronaldo criticised senior figures at Old Trafford and showed his digust towards manager Erik Ten Hag.
Man United and Ronaldo have mutually agreed to end their association early, bringing an end to his second spell at the club.
The five-time Ballon D'or winner had a contract until the end of this season but will have to find a new club in the January transfer window.
"Cristiano Ronaldo is to leave Manchester United by mutual agreement, with immediate effect," read a club statement.
"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."
Following the news, Ronaldo released a statement of his own, saying: "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."
Ronaldo is currently with the Portugal squad preparing for the start of their World Cup campaign against Ghana on Thursday.
