Having moved to the Stadium of Light alongside former Old Trafford colleague Wes Brown this summer, the Ireland defender has recovered from injury to begin his Black Cats career
And the Black Cats boss says the Ireland international should be fit and ready to make his bow for the club against Swansea City in the Premier League on Saturday.
Bruce told The Evening Chronicle: “I was toying with playing John at Brighton, but he'd only been in training for four days.
“We'll need his experience at Swansea and it'll be a big boost to the team. He's someone who I know will be able to handle the situation.
“You can see his influence straight away after he's joined in training. It's huge.
“He's worked like a beast to be fair. He's been at the training ground from 9am every day. His sheer professionalism is excellent and that's why he's been at the top for so long.”
Bruce confirmed that he has no qualms about throwing O’Shea in at the deep end without an outing for the reserves to establish match sharpness first.
“He'll be fine to play against Swansea, he's the type of player who won't need a game beforehand,” said the 50-year-old.
“His physical welfare is very good, but you're always a bit worried with a hamstring. He's done everything right, though.
“I needed to give him ten days of training, and hopefully he'll be in a position to play against Swansea.”
Sunderland are looking to kick-start their season against the newly-promoted Welsh side, having lost consecutive matches to rivals Newcastle in the Premier League and Championship outfit Brighton in the League Cup in midweek.