A few bumps along the way but in end nothing could stop Red Devils
Some of the key matches during that historic campaign:
United 2 Liverpool 1, FA Cup, January 24
The treble was almost over before it had even been spoken about as a possibility. Liverpool led for much of the fourth-round tie courtesy of Michael Owen's second-minute header. However, goals from Dwight Yorke and Ole Gunnar Solskjaer in the final two minutes completed a sensational turnaround and gave United a first victory over their arch-rivals in the competition since 1922.
Arsenal 1 United 2, FA Cup, April 14
A night of incredible drama at Villa Park as the treble dream dangled by a thread. David Beckham put Sir Alex Ferguson's side ahead but the semi-final replay swung Arsenal's way after Dennis Bergkamp's equaliser and a red card for Roy Keane. The Gunners had the chance to win it in injury time after Phil Neville tripped Ray Parlour for a penalty, but Peter Schmeichel saved Bergkamp's spot-kick. An outstanding solo goal from Ryan Giggs in the second period of extra-time saw 10-man United progress to the final.
Juventus 2 United 3, Champions League, April 21
The treble was under serious threat again as the Red Devils found themselves 2-0 down in the Stadio delle Alpi after only 11 minutes and 3-1 behind on aggregate. Keane had been booked and knew he would miss the final should his team get there but he dragged them back into the tie. His header and a strike from Yorke cancelled out Filippo Inzaghi's early double and put United ahead on away goals. Andy Cole scored their third as the Red Devils stunned Juventus in Turin to reach a first European Cup final for 31 years.
United 2 Tottenham 1, Premier League, May 16
Ferguson's team went into the final game of the season a point in front of Arsenal and knowing that victory would secure a fifth Premier League title in seven years. Things got nervy at Old Trafford when Les Ferdinand put Spurs ahead but goals from Beckham and Cole were enough to secure the first piece of silverware in United's treble quest.
United 2 Newcastle 0, FA Cup, May 22
Goals from substitute Teddy Sheringham in the first half and Paul Scholes early in the second period saw United win the FA Cup for a then-record 10th time and complete a third league and cup double that decade.
Bayern M 1 Manchester Utd 2, Champions League, May 26
United continued to do it the hard way right until the end, making a nightmare start to the final at the Nou Camp as Mario Basler's free-kick put Bayern ahead early. The Germans hit the woodwork three times in the second half but somehow Ferguson's team stayed in the match. The treble looked like it had slipped away at the last hurdle but injury-time goals from Sheringham and Solskjaer sealed a sensational comeback victory and rounded off an unforgettable 11 days for the club which had brought three trophies.