In 2017, Lukaku had been signed by Man United after they beat Chelsea to it.
However, he has said he received a phone call from Mourinho in New York convincing him to join the Red Devils over the UEFA Europa League champions.
“I was gone, I was going to Chelsea,” the Belgium international said on the LightHarted podcast.
“I was looking for an apartment, an apartment for my mum to stay in close to the practice facility, so I don’t have to drive too far. And then Man U came.
“At Man U everybody was… I felt the trust more, where everybody wanted me to be there and that’s the true story. People say ‘Yeah, my agent (Mino Raiola)’ and stuff like that – my former agent at the time – he did his job, he got the best opportunity for me, but the people wanted me the most and that was Man U. Everybody was wanting me. There was no doubting.
“They came and they told me – I was in New York – I get a phone call from this number and I’m like, ‘Who’s this?’ Pick up, Jose Mourinho. ‘Rom, how are you doing?’ I’m like, ‘Yeah, what’s up, boss?’
“‘I’m gonna get you back, we’re gonna pay £75m plus £15m in bonuses (add-ons) by next week, so I expect you in LA. So go and do your s**t in LA and I’ll see you after [in pre-season]’. I felt the dude was lying, like ‘I’ll see you’.
“Then the next thing I know, I wake up and had to go back to Everton on the July 7 and July 6, I wake up in the morning and I see they’ve agreed on the deal, so I’m like, ‘Man! They came in hard!’
“I spoke with Ed Woodward as well, he’s like the GM (general manager), we had a good conversation, we spoke twice, I think – and in that conversation, I could feel his trust. While Chelsea it was the coach. Antonio Conte wanted me bad, like bad, he wanted me when he was at Juventus in 2013. We have a really good relationship, we have the same agent. His playing style, he needed me for his team.
“So he showed me an analysis of the game, how he wanted to play, so for him, he won three Italian championships, he did a three-peat before he took the challenge up and one of the three-peats were unbeaten.
“So I was going to Chelsea and then Man U came through and when I felt the trust of everybody at Man U. And the stature and magnitude of the team, I felt like, ‘You know what? It’s too good an opportunity for me, everybody believes in me, it’s a good team, why not?’”