That West Ham's triumph was masterminded by manager Sam Allardyce and greatly influenced by striker Andy Carroll, both former employees of Sunderland's arch-rivals Newcastle United, added further misery for the home side following a lacklustre performance.
The pair's efforts may mean Newcastle are the only club from the north-east of England in the Premier League next season, with a powerful Carroll header giving West Ham the lead inside the first 10 minutes.
And Mohamed Diame's deflected strike just after the break ensured Sunderland remained 19th in the table, four points adrift of safety, despite Adam Johnson's 65th-minute effort.
Sunderland have at least one game in hand on all of their relegation rivals, but with Tottenham, Everton, Manchester City and Chelsea – all in the top six – awaiting Gus Poyet's men in their next four matches, the Wearside outfit face an uphill battle to remain in the top flight.
West Ham, who have now won six of their last nine Premier League fixtures, are 11 points adrift of the bottom three.
Carroll – who was booed immediately due to his St James' Park connections - gave West Ham the lead in the ninth minute with a trademark header, rising above John O'Shea to nod in Mark Noble's corner at the back post.
The sloppy manner in which Sunderland conceded will have infuriated Poyet and his mood will not have brightened when Lee Cattermole spurned two chances to quickly level proceedings from close range, first shooting at Adrian before blazing over.
Carroll headed a George McCartney cross at Vito Mannone, while at the other end, Sunderland felt aggrieved not to win a penalty after Kevin Nolan clearly knocked the ball away with an elbow.
West Ham compounded their woes five minutes after the interval when Diame shot past Mannone.
Just like the opener, the goal was basic but effective, as Carroll chested a long punt down into the path of Diame, and the midfielder met the ball on the edge of the area, firing into the back of the net via Santiago Vergini's deflection.
West Ham should have wrapped up the game on the hour mark, when Stewart Downing was sent through on goal, but Mannone superbly tipped wide, and his excellence allowed Sunderland a lifeline – one taken by Johnson.
The winger, who surprisingly started from the bench despite being Sunderland's top league scorer, netted his eighth Premier League goal of the campaign when he fired into the top-left corner with a fizzing 20-yard effort.
The goal buoyed Sunderland, who ramped up the pressure as Adrian produced a double save to keep out Ki Sung-Yueng and Connor Wickham, while Fabio Borini fired into the side netting.
West Ham were able to stem Sunderland's flow, though, and although the hosts rallied late, Ignacio Scocco's wasted header was the closest they got to a dramatic leveller.
