Santi Cazorla's tumble made for an unsatisfying opener (26) but Mikel Arteta converted a second spot-kick after the break (64) to give an irritable Arsene Wenger a first win in five.
How Arsenal needed an early goal to thaw the chill after defeats by Swansea and Olympiakos but when a Boaz Myhill punch dropped tantalisingly for Gervinho just minutes in, the striker scuffed his shot horribly.
West Brom - beaten for the third game in a row - were forced into a reshuffle, Goran Popov on for an injured Liam Ridgewell, and as an impressive Jack Wilshere surged forward into space, home discord gave way to cautious optimism.
Cazorla curled wide and volleyed another high under pressure but, though Arsenal were the better side, his breakthrough soon after never should have been. Steven Reid swiped at air and seemingly not man as the Spaniard cut back but Mike Jones pointed to the spot and Arteta accepted the gift.
Wilshere slid in to almost add a second seven minutes from the break but Arsenal deliveries had in truth been hit and miss and West Brom lethargic opponents.
The flashpoint made for second-half spice as both sides raised the tempo but glorious chances came - and went - for the home side.
Gervinho found dangerous positions only to flounder with alarming frequency; missing the ball completely, albeit under pressure, just yards from goal, while Lukas Podolski would later shank hopelessly high.
Steve Clarke swapped a peripheral Peter Odemwingie for the pace of Romelu Lukaku but any hope of a fightback was extinguished when Chris Brunt brought down Alex Oxlade-Chamberlain with two flailing legs.
The Arsenal winger tussled with Popov in the build-up but Arteta kept his focus and the job was done.
Wenger's side had hardly been at their best but they hadn't needed to be.