After a sluggish first half, the hosts broke the deadlock in the 49th minute when Andy Carroll bundled home from close range after Allan McGregor fumbled Enner Valencia’s shot.
Morgan Amalfitano dinked home West Ham’s second midway through the half, before Stewart Downing completed the scoring in the 71st minute by breaking through the Hull defence and slotting into the far corner.
Kevin Nolan almost added a fourth late on when his effort from a tight angle came off the woodwork as the Hammers closed out a win which moved them to within four points of fourth spot.
Hull boss Steve Bruce made three changes from the side that lost to West Brom last Saturday as Michael Dawson, Tom Huddlestone and Sone Aluko came in for Maynor Figueroa, Nikica Jelavic and Abel Hernandez.
The visitors started brightly, with Aluko forcing two early corners and Ahmed Elmohamady pulling a shot wide from inside the area when well placed.
For the hosts, Aaron Cresswell saw a long-range shot swerve narrowly wide of the post and James Tomkins head over from a corner.
Aluko squandered a great chance for Hull in the 24th minute when he turned Tomkins to break through on goal, but he took too long and allowed Collins to block the finish.
Moments later, the Nigerian was in again and fed Jake Livermore in the box, but the midfielder failed to find Elmohamady, who was free outside him.
Valencia saw his back-post header loop over McGregor and drop onto the crossbar late on in the half, while Steve Bruce’s injury list had another name added to it in first half injury time when James Chester landed awkwardly and needed to be replaced. It was later confirmed that Chester suffered a dislocated shoulder.
The hosts began the second half strongly, with Nolan firing a shot just over from the edge of the area after Downing’s bursting run and pull-back.
Andy Carroll opened the scoring soon after when a McGregor error saw the Hull keeper palm Valencia’s low strike back across the six yard box, with the striker reacting quickest ahead of Curtis Davies to fire home.
Craig Dawson almost gifted the hosts a second, but after he gave away possession on the edge of the area Valencia drilled into the side netting.
West Ham doubled their lead in the 69th minute when Alex Song and Valencia combined to feed in Amalfitano, who cutely chipped over the on-rushing McGregor from inside the area.
Song was involved again for the third goal two minutes later, with his defence-splitting pass finding the bursting run of Downing, who slotted home.
Kevin Nolan’s hooked cross came back off the bar late on, with defeat putting more pressure on Hull manager Steve Bruce, who has now overseen just two wins in 15 Premier League games.