Sebastian Larsson's stunning goal set up a comfortable 3-0 victory for Sunderland as they dragged themselves further clear of the Barclays Premier League relegation zone.
The Sweden international set the Black Cats on their way with a 12th-minute piledriver, and the game was effectively over when Adam Johnson scored from close range after taking advantage of comical defending by West Ham two minutes after the restart.
James McClean wrapped up the win 16 minutes from time after Stephane Sessegnon had left defenders trailing in his wake, and not for the first time.
The Black Cats started in determined fashion and it took a good block by full-back Dan Potts to keep out Johnson's third-minute volley with David Vaughan steering the rebound wide. Winston Reid had to be similarly stubborn six minutes later after Steven Fletcher surged into the box and went for goal, but the respite was only temporary.
Johnson's right-wing cross was easily picked off by Alou Diarra, but he could only head it to Larsson 25 yards out, and he smashed an unstoppable left-foot shot high past Jussi Jaaskelainen to open the scoring.
Sunderland might have increased their lead with 26 minutes gone when Sessegnon carved his way through the Hammers' defence, but he stabbed his effort wide.
The home side did double their advantage two minutes into the second half when Sessegnon broke from his own half down the right before picking out the unmarked McClean on the opposite flank.
Jaaskelainen pulled off a fine one-handed save to deny the Republic of Ireland winger, but as Potts attempted to chest the ball back to his keeper, Fletcher intervened to poke it towards Johnson, who dispatched it via the post into the unguarded net.
The Black Cats nearly added a third with 57 minutes gone when Sessegnon picked out Jack Colback in acres of space and his initial shot was well saved by Jaaskelainen before his follow-up cannoned back off the upright.
West Ham capitulated once again after 74 minutes when Sessegnon skipped into the box and scuffed a shot to the far post, where McClean slammed the ball home from a tight angle.