Slaven Bilic watched his side extend their unbeaten start to the season as Albion topped the Championship following their 2-0 win at QPR.
Academy graduate Nathan Ferguson continued his impressive start to the season when he fired his first goal for the club in the 53rd minute.
After Yoann Barbet had been sent his marching orders for bringing down Hal Robson Kanu, Matheus Pereira then notched his first for the club after he fired home under the wall from a free kick.
The Baggies controlled the game with Rangers struggling to find a way past the impressive Jake Livermore in Albion's midfield.
Charlie Austin, starting at Loftus Road for the first time since departing Rangers, thought he'd opened his Albion account in the first half but his goal-bound volley was superbly blocked by Barbet.
The game came to life 8 minutes after the break when Rangers allowed Ferguson to bring the ball out of defence, stroll through midfield and then fire a 25-yard drive under Joe Lumley.
Austin stung the hands of Lumley as Albion pressed forward for another goal with substitue Kyle Edwards twice coming close to adding to Albion's lead.
But it was game over when Robson-Kanu burst clear and was brought down on the edge of the area by Barbet. From the resulting free kick, Pereira drilled the ball under the wall to send the Baggies top.