The Baggies returned to winning ways in the Premier League with a narrow 2-1 victory over Arsenal at The Hawthorns.
The Gunners took the lead in the 35th minute through Olivier Giroud, who headed in Mesut Ozil's free kick from the right.
James Morrison volleyed past Petr Cech to restore parity on 35 minutes, before Mikel Arteta diverted McClean's cross into his own net.
Santi Cazorla could have secured a point for Arsenal from the penalty spot, but he slipped at the crucial moment.
McClean has taken to Twitter to express his delight at West Brom’s win against Arsenal.
Great result, tops of a great week, enjoy your weekend #boingboing— James McClean (@JamesMcC14) November 21, 2015
Over the course of the 90 minutes at The Hawthorns, hosts West Brom had just 27% of the possession, took four shots of which just one was on target, and earned three corners.
Arsenal had 73% of the possession, took 11 shots of which only three were on target, and earned five corners.