The German is expected to be named as the Red Devils' interim coach on a six-month basis, before then leaving the hotseat to join the club's hierarchy as a consultant for two years.
It's a move which has gone down well with Red Devils fans, with the German a revolutionary in his homeland famed for mentoring the likes of Jurgen Klopp and Thomas Tuchel at their start of their now blossoming careers.
Klopp and Tuchel credit the 63-year-old for inspiring their own versions of Gegenpressing, a high-octane ball-recovery tactic he has implemented with his teams since the 1980s.
Rangnick is currently the head of sports and development at Lokomotiv Moscow and due to work permit issues, he will not be in charge for Sunday's clash at Chelsea.
But who is Rangnick, how do his teams play and how could Man United line up under Ole Gunnar Solskjaer's successor?
Born in Backnang, Germany, Rangnick studied at the University of Sussex where he used his time in England to play non-league football for Southwick.
Quickly realising his playing career was heading nowhere, a meeting with Dynamo Kiev in 1983 saw the famed Gegenpressing first formed.
From there Rangnick's philosophy was shaped. He went on to take charge of Stuttgart, Schalke and Hoffenheim in the lower divisions of German football and had mixed spells with all three clubs.
Rangnick's impressive role in steering back-to-back promotions with Hoffenheim saw him return to Schalke shortly after.
But his status in the German game really elevated to a new level when he accepting a new challenge in 2012 to take on the role of director of football at both Red Bull Salzburg in Austria and recently-formed German club RB Leipzig.
Over the next seven years the two sides would enjoy enormous success, with Rangnick's 'three Cs' key in their rise.
Concept, competence and capital are the fundamentals needed for 'club-building', in the eyes of Rangnick, which in essence focuses on implementing a specific DNA and finding the best people for each job.
What could this mean for United?
In the past, Rangnick has often used the unusual 4-2-2-2 formation which is rarely seen in the Premier League, which he believes is ideal to exploit the 'red zones'.
Speaking to the Coaches Voice about this style when referencing Red Bull Salzburg's system, he previously explained: "We decided on a formation that, in Germany and Austria, no other team has played - 4-2-2-2.
"A back four, two number sixes - one was more like an eight - two number 10s, and two strikers.
"[Sadio] Mane and Kevin Kampl didn't play on the wing; they played in a 'semi-position' we called 'the red zone'."
With this formation in mind, talkSPORT has identified how United could look under Rangnick for the rest of the 2021/22 campaign.
David de Gea, who's arguably been the Red Devils' best player in their dreadful start to the campaign, will be safe in the XI.
At the back, however, changes could be imminent.
Last year, Rangnick said Luke Shaw 'wasn't on the level' for United and that could see Alex Telles introduced as an offensive left-back in his system.
Shaw had a superb season last time out but has struggled to replicate his impressive campaign and Euro 2020 form into this campaign.
"I know they have Luke Shaw but I'm not so sure if he's still on the same kind of level you need to be for a club like Manchester United," Rangnick told Sky Sports in an interview in September 2020.
Despite Harry Maguire's woeful start to the season, the club captain is likely to start with Raphael Varane at centre-back, whilst the more attacking Diogo Dalot may get the nod over Aaron Wan-Bissaka as Rangnick prefers his full-backs to be more offensive-minded.
In the 4-2-2-2 formation, Rangnick also prefers his deepest midfielders to be as mobile as possible.
When fully fit, Paul Pogba possesses too much quality to overlook and would have to return to the midfield alongside the more defensive Fred or Scott McTominay.
Fred has been one of United's better players in recent weeks, so he'd get the nod ahead of the Scot, while Donny van de Beek would have to rotate with Pogba in the more attacking No.8 position.
In the more advanced midfield pairing, Rangnick could use Bruno Fernandes and Jadon Sancho as two wide No.10's effectively - or the 'red zone' as the tactician calls it.
Fernandes is already a great presser, while Sancho is one name who could well blossom under the German due to his time at Borussia Dortmund, talkSPORT's European football expert Kevin Hatchard believes.
"Jadon Sancho I think will be a real beneficiary of this if it all goes through," he said on Thursday.
"Because he's a guy who, you've gotta bear in mind, has been in German football.
"And he's used to learning about pressing triggers, he's used to learning about when to go and press the opponent, when not to.
"I think part of the struggle at Manchester United is that maybe those instructions haven't been as detailed or haven't been the same - I think he's struggled in that regard.
"I would think he'd be perfect for the way that Rangnick would want to play.
"Because he's the kind of guy that makes decisions quickly and generally makes the right decisions.
"He thrives in that kind of broken transitional play that Rangnick wants to create."
Perhaps the one dilemma that Rangnick has is his task of dealing with Cristiano Ronaldo, who five years ago Rangnick labelled 'too old and too expensive' five when he was at RB Leipzig.
Rangnick will know the Portuguese is undroppable, though, so he'd have to try and counteract that by utilising Edinson Cavani or Marcus Rashford up top with both players used to pressurising defenders.
You can have a look at their potential XI under Rangnick in full, below…