In a statement on Friday, the executive vice-chairman of Manchester United, Ed Woodward, said there was no one better than Mourinho to guarantee success on the pitch.
"Jose is quite simply the best manager in the game today. He has won trophies and inspired players in countries across Europe and, of course, he knows the Premier League very well, having won three titles here," he said.
Complexities over Mourinho's image rights, owned by Chelsea Football Club, caused delays in his appointment, but Manchester United say the issue is now resolved.
His personal sponsorship deal with Jaguar may also be ended early, should Manchester United deem it to be in conflict with the club-wide Chevrolet sponsorship.
Mourinho's salary details have not been released, but tabloid newspaper reports claim the Portuguese manager will pocket £10 million ($15 million) each season.
And, what does the man himself think? It is all sweetness and light, for now:
"To become Manchester United manager is a special honor in the game. It is a club known and admired throughout the world. There is a mystique and a romance about it which no other club can match. I have always felt an affinity with Old Trafford," Mourinho said in the statement from Manchester United on Friday