In-form West Brom accepted Hull's gifts to pile more misery on the Tigers.
Chris Brunt and Gareth McAuley cashed in on errors before James Morrison clinched a 3-1 win for the Baggies at The Hawthorns.
Robert Snodgrass had given Hull a first-half lead, but the Tigers beat themselves during a second half littered with costly defensive mistakes.
Brunt and McAuley were gifted free headers and Mike Phelan's side are without a win in nine games and remain second bottom in the Premier League, three points from the safety line.
In contrast the upwardly mobile Baggies sit eighth, having won six of their last 10 outings to set their second-best points haul in the top flight after 20 games, 29.
West Brom pile more misery on struggling Hull
