Steven Fletcher's eighth Premier League goal of the season proved enough to beat Southampton and lift Sunderland four points clear of the drop zone.
The Saints began well but a Rickie Lambert set-piece was as close as they got before Fletcher steered in a mishit effort from Stephane Sessegnon.
The goal took the wind out of the hosts and Jose Fonte's forceful header was a rare second-half threat to Sunderland.
The visitors coasted home as a comeback failed to materialise.
Sunderland's rich run of form in the early days of Martin O'Neill's reign, just over a year ago, has felt far more distant for the Wearsiders this season.
Sunderland's woe on the road
Sunderland last won away in the Premier League on their visit to Fulham on 18 November. Before that their last victory on the road was a 1-0 win at Stoke's Britannia Stadium on 4 February.
But this victory, combined with seven points from matches over Wigan, Reading and QPR, should reassure fans that they have enough quality to stay clear of the relegation zone.
Southampton have finishing in at least 17th place as their top priority in their first season back in the top flight and have looked far more likely to obtain it recently.
After one win in their opening 11 games, Southampton manager Nigel Adkins has managed to stem the flow of sloppy goals at one end without sacrificing the attractive attacking intent at the other.
Southampton were flat - Adkins
The hosts' confidence was obvious in the opening stages.
Maya Yoshida and skipper Fonte ushered an apparently struggling Fletcher down cul-de-sacs, while Gaston Ramirez's neat touches filled the absence of regular captain Adam Lallana in attack for the hosts.
But for all their pretty approach play, Southampton could not manoeuvre their way into a clear sight at goal.
Ramirez's dipping long-range effort was comfortably dealt with by goalkeeper Simon Mignolet and Lambert fizzed a free-kick a foot wide, before Fletcher's predatory instincts sniffed out the opener against the run of play.
The Scot, substituted at half-time in recent matches against Manchester United and Norwich, had appeared to be hampered by a back injury, but was alert to turn in Sessegnon's shanked shot after Adam Johnson had found space down the left flank.
First scorer Fletcher
Steven Fletcher has scored the first goal in six Premier League matches - more than any other player.
The former Wolves man has now scored with over half of his shots on target in the Premier League this season
Emmanuel Mayuka, on an industrious full debut for Southampton, had his appeals for a penalty turned down soon after as referee Howard Webb ruled that Carlos Cueller's rugged challenge had taken the ball.
But Southampton look deflated to find themselves behind and Craig Gardner's teasing delivery deserved a decisive touch from either Fletcher or Sessegnon as the hosts struggled to rouse themselves after the break.
The introduction of Steve de Ridder injected some life into the home side and Fonte's header was cleared by Jack Colback before Jason Puncheon almost wriggled into a dangerous position on the byeline.
Fletcher delivered for us - O'Neill
But it was not until the last few minutes that Southampton managed to force the Black Cats back into their own penalty area.
Goalkeeper Kelvin Davis came up for a corner but the ball would not settle for Guly Do Prado in front of goal as time ran out and Sunderland clinched only their second win in 17 Premier League away games.
Southampton manager Nigel Adkins:
"Today seemed to be a game that was uncharacteristically flat. We gave Sunderland something that they could hang on to and they did that very well.
"We moved the ball about very well, but we did not get the breakthrough and the Sunderland goal changed the complexion of the game.
"The players have put the effort in but it was not to be. We have to put this one to bed and get ready for Fulham."
Adkins' added that captain Adam Lallana would not recover from a knee injury in time to play against Fulham on 26 December.
Sunderland manager Martin O'Neill:
"It was a big performance from us today, and I am thrilled not only for the team but also the fans who have travelled down today.
"It is a long long time since they had something to shout about. We had to make a few changes we reverted to a back four that have played in recent times and I thought they were terrific.
"Steven Fletcher has scored a lot of us and all of them have been important, there have not been any third goals in three-goal wins. He has been fantastic and at times I think we are struggling to keep up with him."
Corner taken left-footed by Gaston Ramirez, clearance by Steven Fletcher.
Maya Yoshida takes a shot. Save made by Simon Mignolet.
Guly Do Prado takes a shot. Blocked by David Vaughan. Inswinging corner taken left-footed by Steven Davis from the left by-line, clearance made by Jack Colback.
Gaston Ramirez takes a shot. Blocked by Fraizer Campbell.
Steven Fletcher is flagged offside by the assistant referee. Direct free kick taken by Kelvin Davis.
Maya Yoshida fouled by Fraizer Campbell, the ref awards a free kick. Kelvin Davis restarts play with the free kick.
Nathaniel Clyne takes a shot.
Clearance made by Craig Gardner.
Substitution David Vaughan joins the action as a substitute, replacing Stephane Sessegnon.
Inswinging corner taken right-footed by Steve De Ridder played to the near post,
Steve De Ridder fouled by Phil Bardsley, the ref awards a free kick. Luke Shaw takes the direct free kick.
Stephane Sessegnon is caught offside. Kelvin Davis takes the free kick.
Jack Colback fouled by Gaston Ramirez, the ref awards a free kick. Direct free kick taken by Carlos Cuellar.
James McClean delivers the ball.
Rickie Lambert gives away a free kick for an unfair challenge on John O'Shea. Simon Mignolet restarts play with the free kick.
The free kick is swung in right-footed by Steve De Ridder, clearance by Phil Bardsley.
Substitution Jason Puncheon leaves the field to be replaced by Guly Do Prado.
Booking Phil Bardsley goes into the referee's book for unsporting behaviour.
Phil Bardsley gives away a free kick for an unfair challenge on Steve De Ridder.
James McClean sends in a cross, Luke Shaw manages to make a clearance.
Foul by Steven Davis on Steven Fletcher, free kick awarded. Shot comes in from Craig Gardner from the free kick, save made by Kelvin Davis.
Fraizer Campbell concedes a free kick for a foul on Luke Shaw. Free kick taken by Kelvin Davis.
Phil Bardsley takes the direct free kick.
Substitution (Sunderland) makes a substitution, with Fraizer Campbell coming on for Adam Johnson.
Steve De Ridder challenges Steven Fletcher unfairly and gives away a free kick.
Steven Davis takes a shot. Jack Colback gets a block in.
Jack Cork challenges Craig Gardner unfairly and gives away a free kick. Simon Mignolet takes the direct free kick.
Substitution Sebastian Larsson leaves the field to be replaced by Phil Bardsley.
Corner taken left-footed by Gaston Ramirez, John O'Shea makes a clearance.
Steve De Ridder takes the direct free kick.
Booking Adam Johnson is given a yellow card.
Unfair challenge on Steve De Ridder by Adam Johnson results in a free kick.
Craig Gardner gives away a free kick for an unfair challenge on Steve De Ridder. The free kick is delivered right-footed by Steve De Ridder from left wing, Craig Gardner makes a clearance.
The referee blows for offside. Jose Fonte takes the free kick.
A cross is delivered by Stephane Sessegnon.
The offside flag is raised against Steve De Ridder. Free kick taken by Simon Mignolet.
Gaston Ramirez is flagged offside by the assistant referee. Simon Mignolet takes the indirect free kick.
Inswinging corner taken by Steve De Ridder, Jose Fonte takes a shot. Blocked by Jack Colback. Jason Puncheon takes a short corner.
Corner taken by Steve De Ridder, Jose Fonte takes a shot. Jack Colback gets a block in. Short corner taken by Jason Puncheon.
James McClean concedes a free kick for a foul on Nathaniel Clyne. Free kick crossed by Jason Puncheon, Steven Fletcher manages to make a clearance.
Substitution Steven Davis comes on in place of Morgan Schneiderlin.
Free kick taken by Kelvin Davis.
Substitution Steve De Ridder on for Emmanuel Mayuka.
Corner taken by Sebastian Larsson from the left by-line, Maya Yoshida manages to make a clearance. Inswinging corner taken left-footed by Adam Johnson played to the near post, Carlos Cuellar challenges Rickie Lambert unfairly and gives away a free kick.
Adam Johnson takes a shot from just inside the penalty box which clears the bar.
Adam Johnson takes a inswinging corner to the near post, Jack Cork manages to make a clearance.
The ball is crossed by James McClean.
The ball is crossed by Carlos Cuellar.
Corner taken by Morgan Schneiderlin from the left by-line, save by Simon Mignolet.
Long range effort from Craig Gardner misses to the left of the target.
Morgan Schneiderlin challenges Jack Colback unfairly and gives away a free kick. Direct free kick taken by Craig Gardner.
Steven Fletcher gives away a free kick for an unfair challenge on Jose Fonte. Jose Fonte takes the free kick.
Effort on goal by Rickie Lambert from outside the box goes harmlessly over the bar.
The second half has started.
Unfair challenge on Emmanuel Mayuka by Craig Gardner results in a free kick. Rickie Lambert fires a strike on goal direct from the free kick, inswinging corner taken by Jason Puncheon, James McClean manages to make a clearance. John O'Shea gets a block in.
45:00 +1:30 Half time
Half Time It is the end of the first-half.
Jack Cork gives away a free kick for an unfair challenge on Jack Colback. Carlos Cuellar restarts play with the free kick.
Free kick crossed left-footed by Jason Puncheon.
Booking Booking for Sebastian Larsson.
Free kick awarded for a foul by James McClean on Jack Cork.
Assist on the goal came from Stephane Sessegnon.
Adam Johnson delivers the ball,
Assist by Stephane Sessegnon.
41:53 Goal scored
Goal - Steven Fletcher - Southamp'n 0 - 1 Sunderland Goal scored by Steven Fletcher from inside the penalty area low into the middle of the goal. Southampton 0-1 Sunderland.
Jason Puncheon takes a shot. John O'Shea gets a block in.
The ball is sent over by Adam Johnson,
James McClean delivers the ball, save made by Kelvin Davis.
Foul by Maya Yoshida on Steven Fletcher, free kick awarded. Craig Gardner has an effort direct from the free kick.
Craig Gardner crosses the ball, Maya Yoshida manages to make a clearance.
The ball is delivered by Stephane Sessegnon, clearance made by Maya Yoshida.
The ball is crossed by Morgan Schneiderlin, Carlos Cuellar manages to make a clearance.
The ball is swung over by Craig Gardner.
Morgan Schneiderlin concedes a free kick for a foul on Jack Colback. Direct free kick taken by Carlos Cuellar.
Jose Fonte challenges Stephane Sessegnon unfairly and gives away a free kick. Danny Rose takes the free kick.
Unfair challenge on Gaston Ramirez by Craig Gardner results in a free kick. Free kick taken by Gaston Ramirez.
Jack Cork sends in a cross.
Jack Colback concedes a free kick for a foul on Gaston Ramirez. The free kick is delivered right-footed by Jason Puncheon from right channel, clearance by John O'Shea.
Shot by Gaston Ramirez from outside the box goes high over the crossbar.
Foul by Craig Gardner on Gaston Ramirez, free kick awarded. Direct free kick taken by Gaston Ramirez.
Unfair challenge on Adam Johnson by Gaston Ramirez results in a free kick. Simon Mignolet takes the direct free kick.
Centre by Nathaniel Clyne, John O'Shea makes a clearance.
A cross is delivered by Emmanuel Mayuka.
Gaston Ramirez takes a shot. Simon Mignolet makes a save.
James McClean takes a shot. Save made by Kelvin Davis.
Mishit right-footed shot by Emmanuel Mayuka. Save made by Simon Mignolet.
A cross is delivered by Craig Gardner, Steven Fletcher has an effort at goal from deep inside the area missing to the right of the goal.
Sebastian Larsson decides to take the corner short, Sebastian Larsson takes a shot. Save by Kelvin Davis.
The offside flag is raised against Emmanuel Mayuka. Simon Mignolet takes the indirect free kick.
Emmanuel Mayuka fouled by Craig Gardner, the ref awards a free kick. Rickie Lambert has an effort direct from the free kick. Corner taken left-footed by Jason Puncheon from the right by-line, James McClean makes a clearance.
Craig Gardner gives away a free kick for an unfair challenge on Luke Shaw. Morgan Schneiderlin delivers the ball from the free kick right-footed from left wing, save by Simon Mignolet.
Jason Puncheon has shot on goal from just outside the box which goes wide of the right-hand upright.
Jason Puncheon is adjudged to have handled the ball. Danny Rose restarts play with the free kick.
Stephane Sessegnon takes a shot. Save made by Kelvin Davis. Inswinging corner taken by Adam Johnson from the right by-line, John O'Shea produces a header from inside the six-yard box that clears the bar.
The game gets underway.
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