The 63-year-old German will be introduced to the media on Friday and will take charge of the team for the first time at Crystal Palace two days later.
“As all paperwork has now been completed, we will hold an in-person press conference with Ralf Rangnick at Old Trafford at 9:00 am tomorrow morning,” said a United statement.
United confirmed the appointment of Rangnick as Ole Gunnar Solskjaer’s short-term replacement on Monday, just over a week after sacking the Norwegian following a 4-1 humbling at lowly Watford.
But Rangnick, who was manager of sports and development at Russian club Lokomotiv Moscow, had to wait for a work permit to begin his role at Old Trafford.
Caretaker manager Michael Carrick will take charge for a third time against Arsenal at Old Trafford on Thursday, the former United midfielder having overseen a Champions League win at Villarreal and a Premier League draw at Chelsea.
Rangnick will remain as manager until the end of the season before starting a two-year consultancy role at United.
Carrick said on Wednesday that he had yet to speak to the former RB Leipzig boss.
“I am in this position, as I was for Villarreal and Chelsea,” he said. “I’m getting the boys ready for the (Arsenal) game.
“It is pretty much as it was for both games. Because of the process we haven’t been able to (speak).”
United are 10th in the Premier League ahead of the match against Arsenal, 15 points behind leaders Chelsea and six points adrift of fourth-placed West Ham.
The 20-time English champions have won just one of their past eight Premier League matches but will be desperate to take advantage of a kinder fixture list over the next few weeks.