However, despite his best efforts - 24 goals across 38 appearances in all competitions during the 2021-22 campaign - 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, Ronaldo was desperate to leave ahead of the 2022-23 campaign in search of Champions League football.
United were initially reluctant to allow the Portugal star to leave, before eventually accepting the iconic attacker's desire to move on.
However, no clubs showed a serious interest in signing Ronaldo due to his perceived excessive wage demands.
He was thus forced to stay put and things have gone from bad to worse for him over the course of the last month.
Ronaldo often had to settle for a spot on the bench and things got out of hand when he refused to come off the substitute bench in the 2-0 win over Tottenham, before leaving the premises altogether before the final whistle.
His actions didn't go down well with Erik ten Hag, with the Dutchman dropping Ronaldo for the away match against Chelsea - and a departure in the January window now seems even more inevitable than before.
Does his contract allow for an early exit, though?
GOAL takes a look at when his existing deal expires, what kind of money he earns, a potential exist clause 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.
What is Cristiano Ronaldo's Man Utd salary?
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.
Does Cristiano Ronaldo have a release clause in his Man Utd contract?
It's customary in certain countries to have a minimum fee release clause in contracts, but that's not the case in the UK and Ronaldo does not have an exit clause in his existing deal.
That is unlikely to cause any issues, though, as multiple reports have suggested Man Utd would be willing to let go of the attacker on a free transfer to facilitate a move and get his massive wages off the books.
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 were linked during the summer window.
German Bundesliga behemoths Bayern Munich were touted as a possible destination, while a stay in the Premier League seemed to be on the cards at Chelsea - though such a move would undoubtedly have upset United fans.
A return to Serie A was - and probable still 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, also briefly swirled, with the Portugal icon's agent Jorge Mendes said to have been 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.