News of the Colombian striker’s potential move broke early on transfer deadline day but United fans had to wait until 01:30am before the move was finally confirmed.
Manager Louis van Gaal said: “I am delighted Radamel has joined us on loan this season. He is one of the most prolific goalscorers in the game. His appearance-to-goal ratio speaks for itself and, when a player of this calibre becomes available, it is an opportunity not to be missed.”
Falcao added: “I am delighted to be joining Manchester United on loan this season. Manchester United is the biggest club in the world and is clearly determined to get back to the top. I am looking forward to working with Louis van Gaal and contributing to the team’s success at this very exciting period in the club’s history.”
It also means another season without Champions League football for Falcao, but that is not something that has concerned him in the past - indeed not since he was with Porto in the 2009-10 season has he played in UEFA's top club competition.
The player had been looked at by Arsenal and City but both clubs had baulked had the size of the loan fee and his wages.
The 28-year-old scored 11 goals in 20 appearances for Monaco after joining from Atletico Madrid for a fee of around €50 million last year.
Falcao, who missed the World Cup after suffering a serious knee injury, had also been linked with several top European clubs, including Real Madrid.
Financial details were not disclosed but British media reports suggested the deal cost United a fee of £6m before wages.
Meanwhile, United also confirmed the completion of Daley Blind £14m move from Ajax after agreeing a deal for the 24-year-old, who can play in defence or as a defensive midfielder.
United are still looking for their first win under Van Gaal having drawn two and lost one match in the Premier League and crashed out of the League Cup 4-0 to lower league MK Dons.
WHERE WILL FALCAO PLAY?
Internet pranksters have already been taking potshots at Manchester United over the apparently unbalanced team that is resulting from Louis van Gaal's summer purchases - as well as his decisions on who to keep.
And one of those, from Twitter user Tosh, suggests a hilarious new 'questionmark' formation for the Red Devils to squeeze in their talent:
In all seriousness, it's hard to imagine where all the players will fit in. Assuming that Angel Di Maria will remain out wide, then the newly-arriving Daley Blind will probably fit into a more central role than he is accustomed to.
Then there is the question of Wayne Rooney and Juan Mata. Will Van Gaal try to retain Wayne Rooney in the side, or play Juan Mata in the hole behind the two strikers? Early indications are that Van Gaal is not impressed by Mata - so once Robin van Persie is fit, the Dutchman will start up front alongside Falcao (a potentially devastating pairing of penalty box finishers) with the brutal strength of Rooney deployed in the hole behind. After all, Van Gaal made it clear during the World Cup, when speaking about Van Persie, that his team's captains will always start when fit.
Manchester United - possible formation for 2014/15
A left-sided axis of Di Maria, Blind and Rojo looks strong - but United have also spent a huge amount on Luke Shaw this summer. Given the current look of the squad at the moment, he - like Mata - could be a high-profile, big-money signing from the last year who is left on the bench.
A loan move seems a sensible move for United at this stage, particularly given the Colombian striker's recent injury history. Previous reports of a €65m permanent transfer would have represented a significant gamble for United, but a temporary move seems more prudent.
If it's true, then it represents a brilliant move by Louis van Gaal: Wayne Rooney is clearly past his best, Robin van Persie is ravaged by injury and could need surgery, and both Danny Welbeck and Javier Hernandez have left the club.
A huge move for a big name striker - that would be in addition to the other big signings - would restore confidence and fans' faith in the Red Devils. That alone could repay the £10m wage bill: considering the financial importance of the club's glory-hunting fans around the world, letting their position in English football slip still further is simply not an option.
VIEW FROM FRANCE
Ontiou da Sylva, Eurosport.fr: "Falcao was one of the best talents in Ligue 1 and he will surely be missed. Even though he played only six months in France due to his injury, his departure is a big blow for the French league. Having said that, his mind did not seem to be in Monaco and rumours of his departure have been circulating ever since the day he first arrived. Real Madrid appeared to be his preferred destination and it is kind of a surprise he is going to United, and will miss the Champions League yet again - a competition which Monaco will play in this season. His career seems to be driven by the likes of his agent, Jorge Mendes, rather than what is best for him as a footballer."
- Sports & Recreation
- Manchester United
- Wayne Rooney
- Real Madrid
- Louis van Gaal
- Danny Welbeck
- Javier Hernandez
- Robin van Persie