Souness believes Rangnick has not done enough and does not know the Premier League enough to be appointed the manager of a big club like Manchester United.
He also noted that what the Red Devils need at the moment is instant result and not the long term.project of Rangnick.
The 63-year-old was announced as the replacement of Ole Gunnar Solskjaer on Monday, a day after Michael Carrick led the Red Devils to a 1-1 draw with League leaders Chelsea.
Solskjaer was sacked last week after a poor run of results and Rangnick has now been given a six-month deal at the Theatre of Dreams.
Rangnick’s job may begin Thursday when United file out against Arsenal but Souness has written off his chances before he’s even begun.
“I don’t get it, the man’s CV… you wouldn’t go wild, it doesn’t jump out at you, he’s not been super successful,” Souness told TalkSPORT.
“He’s won just one trophy. His talent would appear to go into a football club and develop the structure for it to develop and improve over a five-to-ten year period.
“That’s not what Manchester United need right now, Manchester need it instantly – they need someone to make an impact now.
“There’s a healthy group of players there now there’s no doubt about it, the previous manager Ole didn’t get the best out of them, they’ve got more to give. That’s what you’re judged on.
“Right now Man Utd have an under-performing group of players. Will this guy who has never been in the English Premier League be able to do that? I don’t think so.
“I don’t get this appointment on any level. He’s going to take a consultancy role? Nice pension for him! He’s 63-years-old, lovely job if you can get that sort of work. But I just don’t get this appointment.”
Rangnick’s first test as Manchester United’s boss comes on Thursday when the Red Devils welcome Mikel Arteta’s Arsenal side at Old Trafford.
The German tactician, widely regarded as the father of pressing football, is taking over Man United in 9th position on the league table and about 12 points behind leaders Chelsea.
