The 63-year-old joined from Lokomotiv Moscow, where he was manager of sports and development, and will take over from Michael Carrick until the end of the season.
In many ways Rangnick is partly responsible for Ole Gunnar Solskjaer's demise, albeit inadvertently.
He has helped shape the football of two of United's current biggest rivals in Liverpool and Chelsea, which perhaps contributed towards the Norwegian this season attempting to move away from a counter-attacking style that had brought moderate success during his tenure.
Both Jurgen Klopp and Thomas Tuchel credit the 63-year-old Rangnick for inspiring their own versions of Gegenpressing, a high-octane ball-recovery tactic he has implemented with his teams since the 1980s.
However, chief sports correspondent for The Times Matt Lawton raised concerns about Rangnick's suitability for the job given his lack of experience in the Premier League and likened him to former Liverpool and England boss Hodgson.
He said on 'The Press Box': "If he is so amazing, and I'm not disputed that he is, but to me he sounds like he is Germany's answer to Roy Hodgson.
"That sort of coaching guru, UEFA coaching sort of expert that sounds like he is a very good communicator, a very good teacher.
"We know that Thomas Tuchel was given his first coaching chance under him and stuff like that.
"So clearly he has got something about him, and maybe, actually United are very smart in that when he has this role at the end of this six months - this sort of two-year consultancy role - he could be really effective."