The 27-year-old France international was signed from Southampton for £25 million in 2015, but has become a peripheral figure under United manager Jose Mourinho, making only eight appearances this season.
Sky Sports reported that the fee could rise to £24 million with add-ons.
After United’s 2-0 League Cup semi-final, first leg win over Hull City at old Trafford, manager Jose Mourinho told Sky Sports: “Before the match I was informed by Mr (Ed) Woodward (the club’s executive vice-chairman) that the situation is to close, so Morgan is more than probably going to Everton.
“I am sad and happy, sad because I like him and he could be an option for us, happy because this is what he wants, to play every game and be important in the team.”