The Dutchman, former Barcelona, Ajax and Bayern Munich manager, was seen as the man to bring attractive soccer back to Old Trafford after a series of impressive performances as Netherlands head coach in the 2014 World Cup. He would succeed Moyes as the second manager after Sir Alex Ferguson's departure.
The Netherlands finished third in the World Cup and there was optimism about his appointment for Man United. An FA Cup triumph wasn't enough for Van Gaal to keep his job in 2016 with Ed Woodward sacking him.
Here's a look at a mixed bag of signings.
Ander Herrera was signed by Louis van Gaal for £29million from Athletic Bilbao in the 2014 summer transfer window. Herrera's arrival at Man United was just the start of many that summer.
The midfielder was an integral part of van Gaal and the next manager Jose Mourinho's plans as he played a crucial part in the middle of the park. The tenacity and passion he brought to Man United made him a favourite amongst everybody at the club.
Herrera was more of a creative force at his previous club but at Man United, he tended to be used in more of a sitting role or occasionally box-to-box. He still managed to get 20 goals in his five seasons at Man United.
Herrera produced many outstanding performances in big games including the Europa League final in 2017, where he was man of the match in a 2-0 win against Ajax.
Eventually Herrera turned down a new contract at the club and in 2019 he moved on a free transfer to Paris Saint-Germain.
Luke Shaw was highly regarded as one of England's stars for the future despite only playing two seasons in the Premier League with Southampton. That was enough for Louis van Gaal to shell out £30milion on the talented left back in the summer of 2014.
Shaw initially struggled at the club as Van Gaal was vocally critical of him, criticising his weight and attitude. Just as Shaw was returning to the form which got him signed for Man United, he suffered a serious leg break injury away to PSV Eindhoven in 2015.
After nearly a year out Shaw was back in the side under new manager Mourinho, but it was not long before he was publicly criticised again by his manager. Mourinho took aim at Shaw constantly and the left back struggled for form and confidence during this managerial reign.
Shaw has since back to playing his best under current coach Ole Gunnar Solskjaer, with him winning the club player of the year award for 2018/19 season. Shaw has developed into a regular starter under Solskjaer and is looking like one of the top full backs in Europe right now.
Marcos Rojo was another arrival in the 2014 summer transfer window after an impressive World Cup campaign playing for Argentina. Rojo was seen as one of the promising defenders in the world after his defensive displays led Argentina to the final.
He was signed for £16million from Sporting Lisbon and penned a five year contract with the Red Devils. This was as the club viewed him as the centrepiece for the defence for the coming years.
However, Rojo's time at Old Trafford was covered with regular injuries and the defender struggled to stay fit for a sustained period. His most successful season came under Mourinho in 2016/17.
He featured in 41 games which included a start in the 2017 League Cup final victory over Southampton. Rojo was also known for his rash challenges with his tackling coming under scrutiny from many.
Amazingly, his reckless style of defending did not land him a single red card in his 122 appearances at Man United.
After a loan in the January 2020 transfer window to Argentine club Estudiantes, Rojo returned to Old Trafford but did not feature and was eventually sold to Boca Juniors in 2021.
Daley Blind was another player bought off the back of an impressive World Cup campaign as his performances for the Netherlands saw him join Man United for £13.8million in 2014 from Ajax.
Van Gaal was a big admirer of the versatile player having worked with him with the Netherlands international side.
Blind was used in multiple positions in his time at Old Trafford as he played left back, centre back and defensive midfield. Blind was known as a player who was very technical and liked to bring the ball out and progress the play from deep.
His best performances often came in the 2015/16 season as he struck up a solid partnership with Chris Smalling. Blind started in the 2017 Europa League triumph over his former club Ajax in a 2-0 win in Stockholm.
Blind eventually was surplus to requirements at Old Trafford as Mourinho did not favour him due to a preference in more physical and taller players. Blind was sold back to his former team Ajax in 2018.
Angel Di Maria
After a string of impressive performances for Real Madrid and a man of the match display in the 2014 Champions League final, many were shocked when Angel Di Maria was placed on the transfer list at Madrid.
Man United were never seen as a viable option for the Argentina international as they had failed to qualify for the Champions League. However, the club put in a huge £59.7million offer to Los Blancos which was accepted in the 2014 summer transfer window.
Di Maria got off to an unbelievable start at Man United as the new number seven scored three league goals in his first five games. This was to be the last of his Premier League goals as he managed just one goal in an FA Cup game against Yeovil Town for that season.
Di Maria would only last a season at Old Trafford and it was clear he never really wanted to be there. Constant below-par performances on the field left fans scratching their heads as to why such a great player was faltering consistently.
The large price tag and reputation of the player means Di Maria will go down as one of football's biggest transfer flops despite his great abilities and moments he has produced elsewhere.
Radamel Falcao was once regarded as one of the top strikers in world football as his days at Atletico Madrid were littered with goals. Despite suffering a serious ACL injury in 2014 playing for AS Monaco, Van Gaal lured the striker to Old Trafford.
Falcao was signed on a season loan deal on deadline day of the 2014 summer transfer window. He scored his first goal in a 2-1 win over Everton in October 2014 after an assist from fellow new signing Angel Di Maria.
However, like Di Maria, Falcao underwhelmed and Man United chose not to pursue a permanent deal for the Columbian international. Only four goals were scored by Falcao and he was constantly criticised for his performances by fans and pundits.
Falcao returned to Monaco after his loan ended before going on loan again to Premier League rivals Man United, Chelsea. Falcao will be remembered as a Premier League flop.
Victor Valdes was one of the top goalkeepers of the past generation and won plenty of titles during his time at Barcelona. In 2015, Man United brought him in to provide backup for first choice goalkeeper David de Gea.
Valdes was brought in purely for his experience and was not signed to play a major part on the pitch for Man United. He made his debut in 1-1 draw with Arsenal in May 2015 as a substitute after De Gea left the field injured.
He would go on to make just one more appearance for the Red Devils before being banished from the squad by manager Van Gaal for refusing to play a reserve game.
Valdes eventually left on loan to Standard Liege before signing for Middlesbrough for free in 2016.
Memphis Depay was the first player signed by Man United in the 2015 summer window by Van Gaal. He joined from PSV Eindhoven for a fee of £25million on a four-year contract.
Depay was another player known to Van Gaal due to their time spent together with the Netherlands team. Depay was regarded as one of the biggest prospects in Europe before his move to Old Trafford.
He ended his first season with seven goals across all competitions with just two coming in the league compared to 28 goals in his previous season for PSV.
The standout moment from his first season included his performances in the Europa League last 32 matchup against FC Midtjylland, where he scored in both legs and played a key part in the home tie.
Depay was sold to Olympique Lyonnais in the 2017 January window by Mourinho.
Italian full back Matteo Darmian was brought in by Van Gaal in 2015 to finally address the issues at right back. Darmian was signed for a relatively cheap fee of £12.7million from Torino FC.
Having sold previous right back Rafael due to his defensive liabilities, Darmian was trusted by Van Gaal to bring solidity and defensive assurance to Man United's defence.
Given the stereotype of Italian defenders being very resolute and having a no-nonsense approach with their defending, many thought Darmian would tighten United up at the back.
In his first season, Darmian was not particularly impressive and his below par performances paid the price as he was shifted out of the team with right winger Antonio Valencia taking his place.
One game in particular that showcased Darmian's early struggles was away to Arsenal when the home side went 3-0 up in the first half, with the majority of the play coming down Darmian's side.
Darmian did have a part in the silverware the club won under Van Gaal and Mourinho and was notably impressive in the 2017 Europa League final against Ajax. Darmian started the game at left back and was proving to at least be a versatile squad member in the team.
Eventually Darmian was phased out of the club and sold back to Italy, leaving for Parma in 2019.
The German legend was no stranger to Van Gaal having previously worked with him during his time at Bayern Munich.
After 17 seasons at his boyhood club, Schweinsteiger arrived at Old Trafford for a small fee of £6.5million in 2015.
Schweinsteiger was brought in to bring experience and a winning mentality to Man United as Van Gaal looked to build his side for a potential title charge after a top four finish the previous season.
However, there were some concerns with the German's arrival due to his previous injuries and age at 31.
Those worries turned out to be true as Schwienstiger struggled to stay fit regularly and get a run of matches in the team. His first season produced an underwhelming tally of just a single goal.
With van Gaal's sacking in 2016, Schweinsteiger was banished from the first team squad by new manager Mourinho and made to train with the academy team.
The German eventually worked his way back into the first team and made four appearances across the 2016/17 season, scoring one goal.
The 2014 World Cup winner left for MLS side Chicago Fire in 2017 before retiring from soccer in 2019.
Signing in the same summer as Schweinsteiger - who was seen as a short term option - Morgan Schneiderlin was another midfield addition to Man United in 2015. However, he was brought in to anchor The Red Devils' midfield for the foreseeable future.
Schneiderlin signed from Premier League side Southampton for £25million. His string of impressive performances in three Premier league seasons with the Saints was enough to prove he had what it took to succeed at Old Trafford.
However, like Schweinsteiger, Schneiderlin failed miserably with stamping his authority in Man United's midfield and was frozen out before being sold to Everton in January 2017.
Sergio Romero was signed to provide competition for De Gea in 2015.
Romero did go on to start for the club in the first four league games of the 2015/16 league campaign. However, once De Gea's future was resolved and committed his future to Man United, Romero moved to the bench and was used for cup competitions.
Despite De Gea remaining the number one goalkeeper at the club, Romero continued to excel in the cup matches.
Romero was part of the side that won the Europa League in 2017 playing 12 games along the way, including the final where he kept a clean sheet in a 2-0 win over Ajax.
Anthony Martial was easily the best signing Van Gaal made at Man United with the forward emerging as one of the world's leading soccer talents. Martial signed for the club in 2015 from Monaco for a rising fee of £58million.
Upon even playing a game for the club, Martial was scrutinised by the British press as being a waste of money. That tag would be ripped apart instantly as Martial's debut saw him score a wonderful solo goal on his debut against Liverpool after coming on as a substitute.
That debut goal is up there as one of the most iconic debut moments in Premier League history due to the rivalry with the opposition and it sealing a 3-1 win.
Martial thrived under Van Gaal, scoring 17 goals in his debut season although he struggled to develop further once Mourinho took over. The Portugese boss would often bench the French forward and it seemed only one of Martial and Rashford could be trusted to start during this tenure.
Mournho's departure in December 2018 revitalised many players including Martial, who was playing freely again. Martial looked back to his best under Ole Gunnar Solskjaer with the 2019/20 season seeing him reach his personal best tally of 23 goals in all competitions.