Goals from Peter Crouch, Fernando Torres and Steven Gerrard secured Liverpool's first Premier League win since Boxing Day.
Crouch's goal was only his second in the league this season
The hosts, who had the better of a woeful first half, took the lead when Crouch headed Jamie Carragher's cross past Craig Gordan in Sunderland's goal.
Torres added a second when he collected Crouch's flick and drilled home.
Sunderland had two penalty shouts turned down before Liverpool were awarded one, which Gerrard dispatched.
With his side trailing leaders Arsenal by 20 points before kick-off, Liverpool boss Rafa Benitez knew there could be no margin for error.
The Spaniard made five changes to the side which lost at West Ham in midweek but that seemed to unbalance the team early on.
Lucas Leiva, deployed on the left of midfield, looked particularly uncomfortable as Liverpool relied solely on Gerrard and Torres for any sort of attacking inspiration.
That played into the hands of Sunderland, who tended to double up on both players, and the visitors were seldom troubled.
Roy Keane's men showed little inclination to attack, however, allowing Liverpool to spend long periods camped in their half.
It took 38 minutes for either side to muster an opportunity of any note, Jermaine Pennant beating Daryl Murphy and crossing for Torres to head straight at Gordon.
That was the only attempt on target in a dour first half. The home fans, who staged a 15-minute protest at the club's American owners after the match, were far from happy.
To their relief, Liverpool played with greater urgency after the break and it was not long before they were rewarded.
Nosworthy (right) kept Liverpool at bay throughout the first half
Carragher produced an excellent cross to the back post and Crouch rose above Phil Bardsley to head past Gordon.
Crouch was denied a second when his acrobatic volley was well saved, before Bardsley cleared his header off the line from Gerrard's corner.
Sunderland were having difficulty coping with a rejuvinated Liverpool, and when Crouch put Torres through with a neat header the Spanish striker made no mistake with a low finish to Gordon's right.
On 73 minutes Carragher appeared to block Murphy's shot with an arm, only for referee Rob Styles to reject Sunderland's protests.
The Wearsiders, still without an away victory this season, had another appeal turned down when Javier Mascherano's high foot connected with Liam Millar's shoulder, while Roy O'Donovan poked over from close range.
To rub salt in their wounds, Styles pointed to the spot after Pennant went down under Nyron Nosworthy's challenge two minutes from the end and Gerrard forced the ball home via Gordon's right hand.
Liverpool manager Rafael Benitez:
"I want to say thank you to the supporters, when we needed them they were behind the team.
"Today we knew it could be a tough game so we needed to keep going. Our supporters were waiting and we started the second half well. They were behind us and it was a massive difference.
"As soon as we scored the first goal the game was open. When you have your confidence low it is important to win, so there are a lot of positive things today."
Sunderland manager Roy Keane on his side's two penalty appeals:
"We felt they were penalties. But I didn't feel we were going to get those decisions today.
"I don't want it to sound like sour grapes but on another day I think they might been given our way.
"How we are going to do this season will depend on our home form. Anything we got today would have been a big bonus."
Liverpool: Reina, Carragher, Hyypia, Skrtel, Aurelio (Finnan 46), Pennant, Gerrard, Mascherano, Lucas (Benayoun 61), Crouch (Kuyt 83), Torres. Subs Not Used: Itandje, Babel.
Goals: Crouch 57, Torres 69, Gerrard 89 pen.
Sunderland: Gordon, Bardsley, Nosworthy, Evans, Collins, Chopra (Waghorn 83), Whitehead, Miller, Richardson (Prica 7), Murphy, Jones, Prica (O'Donovan 55). Subs Not Used: Fulop, McShane.
Booked: Miller, Gordon.
Ref: Rob Styles (Hampshire).
BBC Sport Player Rater man of the match: Sunderland's Craig Gordon 7.65 (on 90 minutes).
Please note that you can still give the players marks out of 10 on BBC Sport's Player Rater after the match has finished.