The Portuguese coach is set to take charge at Old Trafford following Louis van Gaal’s sacking by the Red Devils on Monday afternoon.
Mourinho has been hotly tipped as the leading candidate to take over at United ever since his sacking by Chelsea back in December.
Ronaldo played under Mourinho during his spell at Real Madrid and won the La Liga title under the former Inter Milan boss.
And the former Manchester United star is tipping Mourinho to bring quick success to Manchester United.
Ronaldo is quoted as saying by Metro: “He’s already signed, hasn’t he?
“I think it’s good. If it’s something United wanted I think it’s good.
“I hope Manchester United get back to being where they were because it’s an impressive club, but in the last years they lacked an identity a bit.
“And it hurts me seeing United like that because it’s a club I carry in my heart.
“I wish Mourinho can restore them back to the top.”
Van Gaal was sacked by United on Monday after he failed to guide the Red Devils to a top-four finish in the Premier League.
He did, however, leave the club on a high after he guided them to FA Cup glory on Saturday.
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news