Grady Diangana inspired West Brom to a third successive Championship win as Hull imploded at The Hawthorns.
The DR Congo international created goals for Matt Phillips and Semi Ajayi to settle the contest for the Baggies in the second half.
The clash of two teams occupying play-off places at the start of play was level at half-time as Hull skipper Lewie Coyle volleyed in an equaliser after Jean Michael Seri's dreadful error had handed Albion's Jed Wallace the opener.
The Baggies stepped up the pace after the break to stay in fifth place in the table and push play-off rivals Hull down to ninth.
These two teams began the day locked together on 23 points but the Tigers rarely enjoy a trip to The Hawthorns, and this defeat made it seven straight league losses, with 20 goals conceded, at the ground.
They started brightly enough as Manchester City loanee striker Liam Delap hit the by-line and pulled the ball back for Adama Traore, only for it to slide under his foot.
Two minutes later, the normally reliable Tigers midfield kingpin Seri received the ball from goalkeeper Ryan Allsop and in trying to return the pass gave it straight to Wallace, who finished with a minimum of fuss.
Hull came up with a smart equaliser just before half-time as Coyle, wearing a face mask after suffering a fractured eye socket last month, volleyed past Alex Palmer at the far post after Scott Twine had looped a cross over the West Brom defenders.
The Baggies were the better side after the break, with Allsop beating out Brandon Thomas-Asante's shot, but Diangana made his presence felt in the space of six minutes.
A sweeping move from deep in their own half ended with Diangana playing in Phillips for another sharp finish.
Then Diangana turned a defender inside out on the by-line and crossed for Ajayi, whose shot deflected in to settle matters.
West Brom manager Carlos Corberan told BBC Radio WM:
"We made some good pressing and scored the first goal from one of those pressings, and our second half was much better, more aggressive and showed a lot of personality to score the second goal.
[On Diangana]: "Grady is a very special player and if he finds consistency it is very positive for us.
"The important thing for me is creating chances and scoring goals but today Thomas-Asante didn't score but was excellent, one of his best games I have seen him play this season."
Hull manager Liam Rosenior told BBC Radio Humberside:
"It's always horrible, especially when you lose a game in the manner that we did. We gift-wrapped the game to them.
"For 90% of the game we were the better team but in the 10% where we switch off and make errors and don't do professional things, that's what won them the game.
"We've gone toe to toe with a very good team, dominated certain areas but gifted goals at crucial times.
"(Seri) has made a mistake and will hold his hands up and I will hold my hands up because I'm asking the players to play that way - I believe in it.
"In fact, playing that way gets us back in the game and we took complete control, Lewie scored a fantastic goal and for a 15-minute spell in the second half we were completely on top."