Geordie Andy Carroll helped to nudge Sunderland closer to the relegation trapdoor as West Ham all but secured their own Barclays Premier League status.
The England striker powered the visitors into an early lead and midfielder Mohamed Diame extended it five minutes into the second-half on a night when there were no boos for Hammers boss Sam Allardyce.
Substitute Adam Johnson gave Sunderland, who had earlier seen strong penalty appeals go unanswered, hope when he pulled one back with 25 minutes remaining, and keeper Adrian had to pull off a double save to deny Ki Sung-yueng and Connor Wickham.
But ultimately, the Black Cats' depressing home run was extended to just one win in nine league games to leave the bulk of a crowd of 37,396 fearing the worst.
Former Newcastle frontman Carroll needed just nine minutes to plummet even further in the estimation of the home fans when he headed the visitors into the lead in trademark style.
Mark Noble's corner was tailor-made for him to climb high above John O'Shea and Wes Brown to score just his second goal of the season despite keeper Vito Mannone's best efforts on the line.
However, Sunderland, who have not won a Monday night game in 12 years, were aggrieved not to be handed a chance to level as half-time approached.
Skipper O'Shea bundled the ball into the penalty area as the home side staged an attack and opposite number Kevin Nolan appeared to block it with his arm, although referee Howard Webb was unmoved.
But their mood darkened further five minutes into the second half when Diame latched on to Carroll's knock-down and steered a deflected shot past the stranded Mannone to make it 2-0.
Johnson's strike - his 10th of the season - sparked a spirited fightback, but it was all too little, too late for Gus Poyet's men.
Poyet has had cause to rue the fine margins which exist between success and failure during his time on Wearside to date, and he headed for the dressing room at half-time once again reflecting on the fickle finger of fate.
Having once again decided to employ O'Shea, Wes Brown and Santiago Vergini in a three-man defence, he charged wing-backs Phil Bardsley and Marcos Alonso with the task of getting forward to support the men ahead of them, and Bardsley in particular obliged.
The problem was that neither they nor midfielders Liam Bridcutt, Lee Cattermole and Ki could make the most of the Black Cats' more or less even share of possession.
In addition, Sunderland were hampered with their inability to handle the physical and aerial presence of Carroll, who won virtually everything which came his way before the break to give the Hammers an ever-present threat.
There was an inevitability about the opening goal, which came as he rose to power Noble's left-wing corner past Mannone, although the Italian was equal to the test eight minutes before the break after the striker met George McCartney's cross.
In the meantime, Matt Taylor had screwed a long-range effort just wide at full-stretch with Stewart Downing and Diame enjoying the space left behind by Alonso and Bardsley.
The Black Cats had chances of their own with Bardsley thumping a swerving second-minute drive just wide of the far post and Cattermole failing to make the most of good work by Fabio Borini and Ki when he shot tamely at keeper Adrian.
However, they were desperately unfortunate not to be awarded a penalty seven minutes before the break when Nolan appeared to block the ball with his arm inside the box as it reared up off O'Shea.
Sunderland's uphill task increased markedly in gradient by the time 50 minutes had passed when, after Brown had been penalised for a foul on Carroll, the striker laid off James Tomkins' free-kick for Diame to fire home with the help of a deflection off Vergini.
Poyet replaced Cattermole with Johnson and Craig Gardner soon followed as O'Shea departed, and amidst the re-organisation, Downing should really have killed the game off when he got in behind Alonso, but fired inches wide of the far post.
Johnson gave the home side home when he collected Gardner's pass and curled home a 65th-minute shot, and suddenly, the Black Cats were transformed.
Adrian could not hold Ki's 68th-minute drive, but recovered to block Wickham's follow-up as the home fans sensed a change in the tide, but salvation proved to be beyond them as substitute Ignacio Scocco headed over at the death from Vergini's cross.