Everton have agreed a £75million fee with Manchester United for the sale of Lukaku.
The Belgian is expected to undergo a medical and has already been spotted training with Paul Pogba in LA ahead of a prospective move to the Red Devils.
Lukaku and Mourinho, who previously managed the striker while in charge at Chelsea, will get the chance to work together again.
Chelsea themselves were interested in signing Lukaku, but lost out to United.
The 24-year-old, who hit 25 Premier League goals for Everton last term, has had bad blood with Mourinho in the past.
And according to the Sun on Sunday, Lukaku received a text from the Old Trafford boss to prove they do have a ‘special relationship’.
In the text, the report claims Mourinho insisted he is looking forward to working with Lukaku once again.
Lukaku has been at pains to point out he can succeed under any coach, including Mourinho.
“I know I can succeed under any trainer,” he said.
“After leaving Chelsea, I made an analysis of myself to see what could be better.
“But now I can fit under any trainer and at any club.”