However, despite his best efforts - 24 goals across 38 appearances in all competitions - the Red Devils floundered in the Premier League and exited the Champions League at the last-16 stage.
Despite his obvious affection for the Old Trafford outfit, it has now emerged that Ronaldo has asked to leave. GOAL takes a look at when his contract expires, what kind of money he earns, potential destinations and more.
When does Cristiano Ronaldo's Man Utd contract expire?
Ronaldo's contract at Manchester United is due to expire on June 30, 2023.
However, the club have an option to extend the deal by another year, which would take it up to June 30, 2024.
The Red Devils signed Ronaldo from Juventus in August 2021 on an initial two-year deal.
He will be 38 and four months old by the time his contract with the Premier League club concludes in 2023.
Ronaldo earns £385,00 ($466k) a week as part of his contract with Manchester United, according to a report from the Daily Mail.
That means Ronaldo's annual salary at Old Trafford is around £20 million ($24m), before performance-related bonuses and associated financial accoutrements are taken into account.
A desire for Champions League football is understood to be behind Ronaldo's request to leave Manchester United.
The Red Devils finished sixth in the Premier League last season, meaning they missed out on a place at the top table of European football. They have, however, qualified for the Europa League - UEFA's second-tier club competition.
Ronaldo has won the Champions League on five occasions and holds the record for most goals scored in the history of the illustrious tournament, as well as the record for most appearances.
His love affair with the competition, where he has thrived, has led to the nickname 'Mr Champions League' being applied to him.
Which club could Cristiano Ronaldo transfer to?
As one of the most decorated footballers of all time, Ronaldo would have no shortage of suitors for his signature and some of Europe's biggest clubs have been linked.
German Bundesliga behemoths Bayern Munich have been touted as a possible destination, while a stay in the Premier League could be on the cards at Chelsea - though such a move would undoubtedly upset United fans.
A return to Serie A is also a possibility, with Napoli and Roma - where Jose Mourinho is boss - reported as clubs who would be willing to strike a deal.
Meanwhile, rumours of a return to Real Madrid, where Ronaldo won four Champions League titles, have also swirled, with the Portugal icon's agent Jorge Mendes said to be assessing the landscape.
The likes of Paris Saint-Germain would be among the few clubs able to afford the attacker, while an emotional return to Sporting, where his football journey began, is the sort of well worn path taken by many professionals.