The Everton striker was prised away from Goodison Park by Jose Mourinho as United look to strengthen its attacking options after the departure of Zlatan Ibrahimovic after one season at Old Trafford.
United pipped Premier League rivals Chelsea to Lukaku's signature but had to splash the cash in order to get the 24-year-old.
The deal sees Lukaku knock Luis Suarez's switch from Liverpool to Barcelona out of the top-five transfers, but his fee is some way behind the amount United paid for Paul Pogba.
Here, we take a look at football's big movers that now includes Lukaku.
Paul Pogba - Juventus to Manchester United, $A151 million
United lured back their former youth star in 2016 four years after allowing him to leave Old Trafford for Juventus on a free transfer. His first season back in the Premier League failed to produce the fireworks Mourinho will have hoped for as he put in a host of mixed performances - but he did lift the EFL Cup and Europa League.
Gareth Bale - Tottenham to Real Madrid, $A144.2 million
Since swapping White Hart Lane for the Santiago Bernabeu, Bale has gone from strength to strength alongside Cristiano Ronaldo and Karim Benzema. Madrid's BBC have won three Champions Leagues, with Bale scoring in the 2013-14 final after his remarkable solo goal sealed the Copa del Rey at Barcelona's expense in the same season. He won a first LaLiga title last season.
Cristiano Ronaldo - Manchester United to Real Madrid, $A135.2 million
Has £80m ever looked like such good business as when Madrid nabbed Ronaldo from United in 2009? The Portugal international has launched himself into another stratosphere since moving to Spain - with only Lionel Messi for company.
Gonzalo Higuain - Napoli to Juventus, $A127.3 million
After topping Napoli's scoring charts for three successive seasons Higuain did the unthinkable and joined foes Juventus in 2016. His move proved the right one as Juve claimed a sixth successive Serie A title, won the Coppa Italia and reached the Champions League final.
Romelu Lukaku - Everton to Manchester United, $A126.8 million
Lukaku's stats in the Premier League are astonishing, the striker having scored 85 goals in five seasons for West Brom and Everton, so it is no wonder United have signed him up and that he cost a big price.
Luis Suarez - Liverpool to Barcelona, $A110 million
Uruguay international Suarez was an idol for the Liverpool fans after helping turn the Reds back into Premier League title contenders, despite being banned for biting Branislav Ivanovic. Another bite on Giorgio Chiellini at the 2014 World Cup brought a global ban, but that did not stop Barcelona taking him to Camp Nou and he has gone on to form a lethal trident with Neymar and Messi.