Mulumbu was sent off in the 83rd minute of the Premier League encounter between the two sides at The Hawthorns.
The 28-year-old, who replaced Craig Gardner in the 72nd minute, was shown a straight red for catching QPR captain Joey Barton with an elbow.
West Brom suffered a 4-1 defeat to Rangers and are probably back in the mix for the relegation battle.
The Baggies are currently seven points above the Premier League bottom three, and need to bounce back from the home loss.
Tony Pulis’s side are back in league action on Saturday when they host Leicester City at The Hawthorns.