John Lundstram put the Blades on the way to a first win in seven games in the 36th minute when he slotted home a cross at the far post from Mark Duffy, who tormented the Black Cats all afternoon.
Richard Stearman doubled United’s lead in the 59th minute with a fierce header into the bottom corner before George Baldock made it three with a close-range header into the roof of the net moments later.
It was United’s first win since November 17 at Burton, since when they had only taken two points to spiral out of the top-six.
It also ended Sunderland’s three-match unbeaten run as they remained in the drop zone, their job in South Yorkshire all the harder without 12-goal top scorer Lewis Grabban, who was out with a calf injury.
United made the brighter start with Duffy central to their attacking play, unleashing a fierce drive which hit team-mate Leon Clarke in the box.
The hosts should have been ahead in the 14th minute when Duffy found Clayton Donaldson, who had got ahead of his marker in front of goal only to steer the ball across goalkeeper Robbin Ruiter and wide.
It took the visitors 21 minutes to have an attack of note as the game entered a lull with both teams guilty of some sloppy play.
United took the lead when Duffy played the ball across the box, evading everyone apart from Lundstram, who slotted home at the far post.
The 23-year-old has been given a starting role since Paul Coutts suffered a broken leg at Burton and the Scot was in the stands for the first time since that night.
The hosts came close again when Jack O’Connell met Duffy’s floated corner only to head the ball wide.
It took Sunderland until the 43rd minute to have their first shot of note when Aiden McGeady’s fierce drive was blocked by Stearman.
United picked up where they left off after the break, enjoying greater possession and with Donaldson and Duffy causing problems.
McGeady sent a low free-kick across the box for the Black Cats that evaded everyone but two goals in quick succession cemented the win.
Again Duffy was involved for the second, curling a free-kick into the box which found Stearman, the former Fulham and Wolves man powering a header home.
Minutes later and United had a third, Clarke laying the ball back for O’Connell to cross to Baldock, who headed into the roof of the net.
Clarke and Enda Stevens got in each other’s way in front of goal and Donaldson was just denied from Clarke’s low ball across the box.
Sheffield United: Moore, Carter-Vickers, Stearman, O’Connell, Baldock, Lundstram, Basham, Stevens, Duffy (Carruthers 75), Clarke (Lavery 84), Donaldson (Lafferty 89). Subs Not Used: Thomas, Sharp, Wright, Blackman.
Sunderland: Ruiter, Matthews, Browning, O’Shea, Wilson, Oviedo, Gooch (Asoro 67), Gibson, Honeyman (McManaman 79), McGeady, Vaughan (Maja 79). Subs Not Used: Steele,Jones, Love, Embleton.
Referee: Peter Bankes (Merseyside).