The Brighton forward started his career at Old Trafford having graduated from the club's academy setup.
Welbeck then went on to make 142 appearances for the Red Devils, scoring 29 times, before leaving for Arsenal in 2014.
While injuries plagued the striker's time with Man United and Arsenal, Welbeck is proving that age is just a number with some stunning performances of late.
While 34 years of age, Welbeck has scored eight times for Brighton this term with the latest coming in the extra-time victory over Newcastle in the FA Cup on Sunday.
By contrast, that tally of eight goals is more than both Joshua Zirkzee and Rasmus Hojlund.
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Joshua Zirkzee has scored seven times in all competitions, while Rasmus Hojlund has just five to his name.
Welbeck has seven in the Premier League, which is more than Zirkzee (3) and Hojlund (2) combined.
Praising Welbeck's performance during his appearance on the BBC, Man United legend Rooney said: "Danny, he's great to play alongside and if I'm being completely honest, I'd would probably still like to see him here playing for Manchester United.
"He scored goals throughout his career, had injuries in early part of his career, but seems to have got over them and he's having a fantastic season."
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Rooney isn't the first ex-Red Devil to urge his former club to re-sign Welbeck, with Gary Neville previously saying: "He was let go too quickly at United.
"If you think about Louis van Gaal, his style of play is very precise, now Danny Welbeck wasn't precise in his game back then, so he (Van Gaal) just let him go. He didn't fancy him at all.
"But he's actually perfect for how Manchester United should play.
"Threatening space in behind, playing off front players.
"This idea that he's not good enough for Manchester United is absolutely rubbish.
"He's good enough to be in a pool of three or four strikers at United.
"For instance, Liverpool have three, four, five forward players across their forward line. They're all of differing abilities and different types."
Man United will be hoping to finish the season on a high after being eliminated in the FA Cup by Fulham on penalties on Sunday.
With the club sitting 14th in the table and already eliminated from the League Cup and FA Cup, it means that Ruben Amorim's side are relying solely on success in the Europa League if they're to qualify for Europe next term.
Despite those targets, Amorim stated that the goal for Man United will be to challenge for the Premier League title again, something that Rooney disagreed with.
"I try to relax the players and they know that it (penalty shootout) is something that is technical but you have to be relaxed and confident," Amorim told the BBC.
"The goal is to win the Premier League. I know that we are losing games but the goal is to win the Premier League again.
"I don't know how long it will take. We have a goal and we continue forward no matter what.
"It's impossible to know but you start understanding the players are better and we understand the league. We'll see in the future.
"It's really important but we have to recover the players. They were really tired and we have three days and then here at Old Trafford against Arsenal."
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Rooney reacted, saying: "I think he'll get time (Amorim).
"It's not a free hit because he'll expect more from Man Utd then what we're seeing since he's been in.
"It's very difficult to come in during the season and have no pre-season, but he has to look to the future and moving forward.
"He says winning the Premier League, how can they compete? To get further up the table, I think that's the next step for them.
"Managers aren't getting that time over the last ten, 15 years. You have to be selfish as a manager and say 'okay, if I don't do it now I might not get that time.'
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"I think it's a little naive to say they're looking to win the Premier League because from where they are now, they're a long way off that."
Man United are next in action on Thursday when they face Real Sociedad in a crunch clash in the Europa League.