United’s captain was in the right place at the right time twice in the second half with a close-range tap-in and then a header.
It was the least Chris Wilder’s team deserved after a performance full of swagger that gave the Blades their first win on this ground since November 1986, when their captain was only 10 months old.
It would have been a much greater margin of victory but for Rovers goalkeeper David Raya, who distinguished himself, but ultimately there was to be no reward, as United notched a fourth win in five away games this season.
The result ends Blackburn’s 25-match unbeaten home run – a post-war club record – but they were outclassed by a more accomplished team.
Adam Armstrong was recalled after his goal-scoring cameo against Nottingham Forest at the weekend. Derrick Williams returned from injury in the other change for the injured Ryan Nyambe.
The early exchanges were dominated by probing United passing, ultimately unlocking a chance for Mark Duffy in the 25th minute, who swivelled and let fly with a rasping low drive that Raya did well to parry behind – a theme of the first half.
Sharp’s looping header soon after caused panic in the Blackburn box, and while Harrison Reed and Bradley Dack saw shots blocked, these were only fleeting sights of goal before Raya was called into action again.
First, he repelled a powerful downward header from former Rover Jack O’Connell and before the half ended, the Spaniard superbly tipped over a curling David McGoldrick effort before palming away John Fleck’s thunderous shot as the Blades moved through the gears.
Reed made a crucial block from Fleck after the restart, before O’Connell headed over from a corner when well placed.
Rovers changed shape and saw Amari’i Bell head over a fizzed Elliott Bennett cross, but United got the goal their play deserved in the 66th minute through a typically flowing move that saw Fleck play in McGoldrick on the left.
His searching low cross was met by the sliding Sharp, whose initial effort was partially blocked but he recovered to tap into the empty net.
And Sharp put the gloss on a dominant performance 11 minutes from the end, when he was on the end of an inch-perfect Enda Stevens cross to head in his eighth of the season from close range.
Substitute Conor Washington found the inspired Raya in his way late on, but it did not matter as the Blades soared to joint top of the league.