In a brief statement, United said the decision, which comes a week after Ronaldo gave an explosive TV interview about his frustrations at the club, was made by mutual agreement.
“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,” the statement said.
“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 is currently with the Portugal national team in Qatar for the World Cup and said on Monday that the timing of his recent comments about United wouldn’t affect the concentration of his Portuguese teammates.
In an interview with Piers Morgan for TalkTV released just before the start of the World Cup, Ronaldo explained how he felt United had betrayed him and that he has no respect for manager ten Hag.
Ronaldo’s departure from United brings the 37-year-old’s second spell at the club to an acrimonious and disappointing end having scored just once in 10 Premier League appearances this season.
He has largely been used as a substitute by Ten Hag and last month refused to go onto the pitch against Tottenham Hotspur, instead walking down the tunnel with minutes of the match still remaining.
This is likely to be Ronaldo’s last appearance at a World Cup, and beyond that it is unclear which club will sign him for the second half of the season.
When he first joined United in 2003, Ronaldo transformed himself from a tricky, skilful winger into one of the best players in the world.
He won three Premier League titles, the FA Cup, two League Cups, the Champions League, and the first of his five Ballon d’Or crowns before moving to Real Madrid in 2009.
Ronaldo’s return to United from Juventus last year was greeted with much fanfare by the club’s supporters, but his second period at Old Trafford failed to match the success of his first as United ended last season without any trophies.
“Following conversations with Manchester United we have mutually agreed to end our contract early,” said Ronaldo in a statement.
“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.”