2021–2022: 100 Premier League goals and team struggles
Ronaldo's re-signing with Manchester United was announced by Juventus on August 27, 2021, with the agreement of personal conditions, visa requirements, and a physical. The deal was officially confirmed on August 31 and was for an initial sum of £12.85 million with a two-year contract plus an optional year. Following Edinson Cavani's decision to transfer to number 21, Ronaldo was given the number 7 jersey. Following his transfer to Paris Saint-Germain, Ronaldo reportedly sold more shirts in the first 24 hours than Messi had in the previous 24 hours combined.
Ronaldo made his second Old Trafford debut on September 11 by scoring the first two goals in a 4-1 league victory over Newcastle United. On September 29, he passed Iker Casillas as the participant with the most appearances in the Champions League when he scored the game-winning goal in injury time in United's 2-1 victory over Villarreal at home. Ronaldo scored the game-winning goal in the final seconds to help United defeat Atalanta 3-2 at home in the following Champions League match on October 20. On November 2, he scored both goals, including the game-tying goal in the final seconds of the opposite match against Atalanta.
Ronaldo opened United's 2-0 victory away at Villarreal on November 23 to become the first player for an English club to score in five straight Champions League games. Ronaldo's six goals were essential to United's group-winning performance and round of 16 qualification. Ronaldo reached the milestone of 800 goals in his career on December 2 by scoring twice in a 3-2 home league victory over Arsenal.
After experiencing a strained relationship with his teammates and interim manager Ralf Rangnick the following month, Ronaldo's team's performance suffered throughout the season. Ronaldo also equaled his worst goal-scoring drought since 2010 while playing for Real Madrid, going two months without a goal. However, he scored his first goal of the new year on February 15, 2022, when Manchester United defeated Brighton & Hove Albion 2-0 at home.
After missing the Manchester derby against Manchester City due to a hamstring injury, Ronaldo returned to action on March 12 and scored a hat-trick in a 3-2 victory over Tottenham Hotspur to break Josef Bican's record for most goals in a career in professional football. However, the Football Association of the Czech Republic claimed that Bican had actually scored 821 goals in his career. Cristiano Ronaldo defeated Norwich City 3-2 on April 16 to record his 50th club hat trick. In a 3-1 loss to Arsenal on April 23, he scored his 100th Premier League goal. He was named the Premier League Player of the Month for April after scoring in the following games against Chelsea and Brentford.
He was named to the Premier League Team of the Year and was the recipient of United's Sir Matt Busby Player of the Year award, given to the team's best player from the previous season, when the season ended. However, with United finishing in a disappointing sixth place and failing to qualify for the playoffs, he was only the third-highest goalscorer in the league behind Golden Boot winners Son Heung-min and Mohamed Salah.
2022: Final season and departure
His agent Jorge Mendes began negotiating with various clubs for a transfer on loan or on a free transfer, including Bayern Munich, Paris Saint-Germain and Chelsea, with the latter club's new owner Todd Boehly being keen on a possible transfer. However, due to his age, overall cost of a transfer and high wages demands, multiple European clubs rejected the opportunity to sign him, including Chelsea after their manager Thomas Tuchel did not approve his signing.
With Chelsea's new owner Todd Boehly interested in a potential move, his agency Jorge Mendes started talks with a number of teams for a transfer on loan or for free, including Bayern Munich, Paris Saint-Germain, and Chelsea. However, a number of European clubs turned down the chance to sign him due to his age, the overall cost of a transfer, and his exorbitant wage demands, including Chelsea after their manager Thomas Tuchel objected to the deal.
Ronaldo only participated in Europa League games after failing to obtain a transfer, losing his spot in the starting lineup to Marcus Rashford and Anthony Martial. On September 15, against Sheriff Tiraspol, he scored his first goal in the competition at the age of 37 by converting a penalty to make it 2-0. Ronaldo was not used as a substitute in United's 6-3 loss to Manchester City on October 2, according to ten Hag, who said that he did so out of "respect for his big career."
In a 2-1 victory over Everton on October 9, Ronaldo entered the game as a substitute and scored his 700th club goal. Ronaldo was disciplined by Ten Hag by being omitted off the squad for a match against Chelsea and being forced to practice separately from the first team ten days after he refused to be utilized as a substitute during a home game against Tottenham and fled the field before the final whistle. Ronaldo returned to practice after talking with the manager, making his home debut against Sheriff on October 27 and scored the third goal to secure United's advancement to the knockout round of the Europa League.
In an interview with Piers Morgan that was published on November 14, Ronaldo claimed that Ten Hag and senior executives had "betrayed" him and had wanted him to leave the team. He also claimed that the club had cast doubt on his account of his daughter's illness, which had caused him to miss preseason, and that he did not respect Ten Hag "because he doesn't show respect for me," which had left him dissatisfied with the club's communication. Despite adding that he regretted his early departure, Ronaldo claimed that ten Hag purposefully irritated him by leaving him on the bench against City and then wanted to bring him on against Tottenham in the dying seconds.
Additionally, he questioned Rangnick's hiring from the previous campaign because he was a "sporting director and not even a coach." Despite anticipating advancements in "technology, infrastructure," Ronaldo claimed there had been "no evolution" at the club following the departure of previous manager Alex Ferguson in 2013. Ronaldo called United a "marketing club" and asserted that the Glazer family "did not care about the club" because he never interacted with them. Following the interview, which was broadcast in two parts on November 16 and 17, United started investigating whether Ronaldo had violated his contract and considered terminating it. Ronaldo's contract was mutually terminated on November 22 with immediate effect.