After a drab first half at the King Power these two Midlands clubs split three goals in the second 45 but it was West Brom who left with the points after Matt Phillips' winner.
James Morrison had put the Baggies in front shortly after the turnaround but led for just minutes as Islam Slimani pulled one back. Then Phillips was on hand to give his side the win after being slid through on goal.
Tony Pulis's side ended a five-game winless run to move up to 11th as the Foxes tumbled to 14th after another failure to win following a Champions League game.