Having sacked Wilder following last season’s play-off final defeat by Sunderland, the win gives some optimism to Sheffield United after a terrible start to this campaign.
His successor Ruben Selles led the Blades to five successive losses before being replaced by Wilder for his third spell at the club, which began with a 1-0 loss at home to Charlton Athletic last week.
But a further week under Wilder and long-serving assistant Alan Knill proved enough to begin a turnaround as they got a win for the first time since beating Bristol City 3-0 in the second leg of the play-off semi-finals on 12 May.
The Blades had scored only once in the league all season before kick-off while their opponents – one of Wilder’s former clubs – had only got their first win of the season last week at Bristol City.
Oxford started the brighter as Brian De Keersmaecker impressed in midfield and Brodie Spencer headed over in the 28th minute after a Przemyslaw Placheta cross as the hosts controlled much of the first half.
Despite Oxford’s dominance of the ball the Blades should have gone into half-time ahead when Campbell managed to blast wide from near the penalty spot after a perfect 41st-minute pass from Gustavo Hamer.
A minute later De Keersmaecker saw a deflected shot from the edge of the box saved as the Blades struggled to clear another Placheta cross.
Campbell had another chance 12 minutes after the restart when his cross-shot was scrambled away before Sydie Peck headed straight at Jamie Cumming after the resulting corner.
Having failed to score in their previous five league games the Blades finally found the net when Chiedozie Ogbene pulled the ball back from the byeline and O’Hare controlled well 10 yards out before hitting a right-footed finish into the bottom corner.
Oxford could have been level late on as Leigh hit the post having swivelled and shot well after controlling Michal Helik’s cross, before Sam Long headed wide of the near post in stoppage time after a ball in from Stanley Mills.
But the Blades defence held out for a rare and morale-boosting victory – one their fans hope will see then club turn a page and begin a rise up the table.