Many will think the club have done well to receive £74 million for a player that didn’t fit Ole Gunnar Solskjaer’s system at Old Trafford.
However, after not replacing him, some are of the opinion that they should have kept hold of the Belgian.
And it’s hard to define Lukaku’s two-season United career.
Having signed for £75 million from Everton, he scored 42 goals in 96 appearances. Not a bad return.
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So where did it all go wrong for Lukaku and why were fans - and those at the club - so keen to get rid of him this summer?
Well, in a very honest podcast before he completed his move, Lukaku has revealed all.
"They have to find somebody," Lukaku told the LightHarted Podcast.
It is Pogba, it is me or it is Alexis. It's the three of us all the time.
"A lot of people don't think I should be part of that system. That's my feeling from the conversations that I have, I just know.
"For me, the thing that makes me laugh a lot is... how the hell is s**t going bad in my team, but when I play in my national team, it's good? And I'm happy.
"I didn't play the last six weeks of the league, like the last three weeks or something before the end of the season and then I had another three weeks off before I had to play for the national team, and then we go and play with the Belgium team and... rollin' and I was there.
"And nobody there complains because I think the perception in my country is changing slightly. A lot of people were saying a lot of stuff. For me, it took years for a lot of people to change their perception. Man U might not get that time. It's s***t that it happens like that.
"When I go and play for my country, we play the style of play that we want to play probably with Man United and I do well over there."
Lukaku then went on to speak about the rumours that were circulating at the time linking him with a move away from United. And the forward felt that the club didn't treat him with too much respect.
"I think a lot of stuff has been said, where I didn't feel protected," Lukaku added. "A lot of rumours, 'Rom is going to go there, they don't want Rom' and nobody came out and shot it down."
“It was for a good three-four weeks. I’m waiting for someone to come out and shut it down. It didn’t happen. I had my conversation, told them it was better to go our separate ways. If you don’t want to protect somebody, all these rumours come out. I just wanted you to say Rom is going to fight for his place, but it never happened for four-five months.
“It was all he’s got to go, he doesn’t deserve to be there, well OK, then I want to go now. There is fighting for your position, but also being somewhere that people want you to be.
“If you’re happy, you find a way, it doesn’t matter if you’re on the bench or starting. But nobody told me that was the situation, so I thought for two-three weeks to analyse, see all this s**t coming out in the media. Who leaks it? Not me. Not my agent. I see it on my phone come out of nowhere.
I told them it’s not good for me to be at a place where I’m not wanted. We’re not stupid. They consider us dumb, but we are not dumb, we know who is doing leaks and stuff. I told them, you can’t be working like this, it’s better for me to go now.
“You don’t want to keep an unhappy player and you clearly don’t want me to be here either.”News Now - Sport News