It ends a two-year spell in charge at Old Trafford that was filled with more humiliating results than many managers of the side have suffered.
Sportsmail has had a look back at Van Gaal's 10 worst matches during his time with United...
Louis van Gaal has his head in his hands, a sight Manchester United fans would become familiar with
United's players walk off the pitch after their 3-0 humiliation against Tottenham in the Premier League
LOUIS VAN GAAL'S RECORD
Games - 103
Wins - 54
Draws - 25
Losses - 24
Win per cent - 52.43
Manchester United 1-2 Swansea City (Premier League, August 16, 2014)
First impressions always count. Van Gaal had benefitted from a summer in which the majority of the Old Trafford faithful had welcomed his arrival for one reason and one alone - he was not David Moyes.
Unfortunately for Van Gaal the image was almost immediately shattered after he failed to beat Swansea in his first competitive game as Manchester United manager. Even Moyes had managed a win in his first game, against the same opposition but away from home.
Gylfi Sigurdsson got the winner for Swansea in the 73rd minute to start Van Gaal's reign in the worst way possible.
Man Utd: De Gea; Jones, Smalling, Blackett; Lingard (Januzaj 24), Fletcher, Mata, Herrera (Fellaini 67), Young; Hernandez (Nani 45), Rooney.
Van Gaal looks on in confusion as United lose his first game as manager against Swansea at Old Trafford
Swansea midfielder Gylfi Sigurdsson scored the winner for the Welsh club in the final 20 minutes of the tie
MK Dons 4-0 Manchester United (Capital One Cup, August 26, 2014)
Will Grigg has become an internet sensation over the last month after firing Wigan to the Championship but he was already making headlines in 2014 after condemning Van Gaal to an embarrassing loss in his first introduction to English cup competitions.
Admittedly the Dutch manager chose to name an incredibly inexperienced side but he still would have expected a victory against the League One side. He would never have anticipated such a damaging defeat.
Grigg got the humiliation underway with a double before then-Arsenal loanee Benik Afobe added two of his own to knock Man Utd out of the League Cup in the second round.
Man Utd: De Gea; Vermijl, James, Oliveira, Evans; Keane, Janko (Pereira 45), Kagawa (Januzaj 20); Hernandez, Welbeck, Powell (Wilson 57).
Van Gaal can barely watch as his team lose 4-0 to League One side MK Dons in the Capital One Cup
An inexperienced side had been selected by Van Gaal but it still did not forgive the nature of the humiliation
Arsenal 3-0 Manchester United (Premier League, October 4, 2015)
The Gunners have often been regarded as weak when it comes to facing the top teams in the Premier League, but they put that aside in stunning fashion in October 2015.
Arsenal simply blitzed Man Utd, scoring three goals in the opening 20 minutes to put the game beyond the Old Trafford side before it had really got going.
Alexis Sanchez and Mesut Ozil scored a goal apiece in just 74 first-half seconds before Sanchez added a third to give Arsenal only a second win in 14 league games against Man Utd.
Man Utd: De Gea; Darmian (Valencia 45), Smalling, Blind, Young; Carrick, Schweinsteiger, Mata (Wilson 82); Depay (Fellaini 45), Rooney, Martial.
Alexis Sanchez scored a third goal for Arsenal in the opening 20 minutes to condemn Van Gaal to defeat
Manchester United 0-0 PSV Eindhoven (Champions League, November 25, 2015)
A draw may not seem like an obvious game to include in a litany of failure, but the context of the game is incredibly important.
Victory against PSV would have ensured that Man Utd would have been involved in the knockout stages of the Champions League this campaign.
However, in typical Van Gaal fashion they could not fashion up a goal at home and therefore had to go to Wolfsburg and get a result to guarantee progress.
Man Utd: De Gea; Darmian (Mata 85), Smalling, Blind, Rojo; Schneiderlin, Schweinsteiger (Fellaini 58), Lingard; Depay (Young 59), Rooney, Martial.
A victory against PSV Eindhoven would have guaranteed progress to the knock out stages for Van Gaal
However, his players could not even muster a goal at home
Wolfsburg 3-2 Manchester United (Champions League, December 8, 2015)
They could not get that result. Everything seemed fine for Van Gaal with 10 minutes played after Anthony Martial put his side ahead, but only two minutes later Wolfsburg responded through Naldo.
Vieirinha dealt Man Utd a hammerblow in the 29th minute as he sent the Wolves ahead and Man Utd struggled to respond. In the 82nd minute they were given a lifeline as Josuha Guilavogui turned the ball into his own net. Another goal would have met progress.
It was not to be. The behemoth Naldo rose to head home and condemn Van Gaal to an early exit.
Man Utd: De Gea; Varela, Smalling, Blind, Darmian (Borthwick-Jackson 43); Schweinsteiger (Carrick 69), Fellaini, Mata (Powell 69); Lingard, Depay, Martial.
The draw with PSV meant United went to Wolfsburg needing a win to guarantee progression to the next round
They could not get that victory, with Naldo popping up in the last 10 minutes to condemn Man Utd to a loss
Manchester United 1 Norwich 2 (Premier League, December 19, 2015)
This defeat felt like a nadir for Van Gaal. Norwich came to Old Trafford with Man Utd on a five game losing run. They left having condemned them to defeat number six.
United were booed off the pitch to increase the brewing pressure on Van Gaal. Cameron Jerome got the game off to a bad start for the Dutch manager with a strike in the 38th minute.
It got worse with a 54th minute goal from Alex Tettey after a clever assist by Jerome, and although Martial reduced arrears it did not temper the poisonous atmosphere inside the ground.
Man Utd: De Gea; Young, Jones, Smalling, Blind; Carrick, Fellaini, Mata; Depay, Rooney, Martial.
Van Gaal watches on as United fall two goals behind in the game against Norwich, who went on to be relegated
Cameron Jerome scored the first goal of the game before setting up Alex Tettey to score Norwich's second
Manchester United 0 Southampton 1 (Premier League, January 23, 2016)
This was a dour game. That was obvious throughout. Manchester United only mustered up a single shot on target in a home game, which was an indication of how reasonable a lot of the criticism of Van Gaal's playing style had been.
Unfortunately it was not just a lack of goals on the home side's part that horrified the fans on this day. Charlie Austin popped up in the 87th minute to score after being brought on from the bench, making it all seem worse.
Van Gaal claimed he had gone for victory: 'I wanted to win this game and that's why I changed Cameron Borthwick-Jackson for Adnan Januzaj. That is a risk you take, it was a poor game and we didn't create so much and neither did our opponent.'
Man Utd: De Gea; Darmian (McNair 60), Smalling, Blind, Borthwick-Jackson (Januzaj 86); Schneiderlin, Fellaini (Mata 45), Herrera; Lingard, Rooney, Martial.
There had been increasing criticism of Van Gaal's playing style, which was not helped by the Southampton tie
Charlie Austin headed home after coming on as a substitute to give Ronald Koeman's team an away win
Midtjylland 2 Manchester United 1 (Europa League, February 18, 2016)
It's fair to say that no one took Midtjylland particularly seriously when they were pulled out of the hat to face Man Utd in the Europa League. There were discussions of their sabermetrics tactics and focus on set pieces, but everyone still assumed United would come through fine.
While they eventually qualified over the two legs, they did not come through the away tie fine - far from it. David De Gea suffered an injury during the warm-up. Memphis Depay put them into the lead but after a series of clever substitutions it was essentially one-way traffic, with Van Gaal unable to respond.
Pione Sisto scored the equaliser for the Danish champions before Paul Onuachu struck a winner from the edge of the area to humiliate the giants.
Man Utd: Romero; Love, McNair, Smalling, Blind; Carrick, Herrera (Schneiderlin 72), Mata (Pereira 78); Lingard, Depay, Martial.
All seemed well for Van Gaal in the opening exchanges after Memphis Depay scored but that would all change
Pione Sisto scored the opening goal for Midtjylland before Paul Onuachu's winning goal embarrassed United
Tottenham 3 Manchester United 0 (Premier League, April 10, 2016)
If there was ever a game to symbolise Man Utd's relative fall under Van Gaal then this was it. Prior to taking the job at Old Trafford he considered an approach from Spurs but chose to head north. Mauricio Pochettino became the head coach in his place.
Spurs got attractive exciting football played by homegrown players while, by the time this game rolled around, Man Utd's football was stodgy and looked unlikely to lead to anything of note by the end of the campaign.
The goals came in one 10 minutes blitz. Dele Alli got it underway, Toby Alderweireld doubled the lead four minutes later, and by the time Erik Lamela slotted the ball past De Gea the humiliation was complete.
Man Utd: De Gea; Fosu-Mensah (Darmian 68), Smalling, Blind, Rojo; Schneiderlin, Carrick, Mata (Depay 76); Lingard, Rashford (Young 45), Martial.
Van Gaal turned down of Tottenham and that would have been little solace when he saw his team lose 3-0
Dele Alli scored the first for Spurs before a further two goals in 10 minutes put the game beyond doubt
West Ham United 3 Manchester United 2 (Premier League, May 10, 2016)
Man Utd's failings had been covered up by Manchester City's own issues in the Premier League, and a draw against Arsenal for Manuel Pellegrini's club meant United had their Champions League destiny in their own hands.
Win both of their remaining games and they would qualify. It sounds simple enough, and when Anthony Martial struck twice to turnaround this game and put Man Utd into a lead in the 72nd minute, things seemed to be going swimmingly.
Not quite. Michail Antonio equalised before Winston Reid secured a win for the Hammers that made it unlikely that Van Gaal would qualify for the Champions League again, and therefore keep his job.
Man Utd: De Gea; Valencia (Januzaj 87), Smalling, Blind, Rojo; Schneiderlin (Carrick 45), Mata, Herrera (Lingard 83); Rooney, Rashford, Martial.
David de Gea cannot keep out Winston Reid's header, hindering United's hopes of the Champions League
