Tony Pulis had been on the lookout for a new number two following the retirement of Dave Kemp and has somewhat surprisingly turned to Megson, who has been out of football since leaving Sheffield Wednesday in 2012.
Megson was appointed as Baggies boss 17 years ago, rescuing them from relegation to the third tier before earning them their first ever promotion to the Premier League in 2002.
“I’m really pleased. I’ve known Tony a long time and although we’ve never lived in each other’s pockets we have similar views on how football should be played and how footballers should behave,” he told the club’s official website.
“I loved my time here although it’s a long time ago now. You obviously have the club you grow up supporting which you always consider to be your club. But this is as close to that relationship as possible – and I can’t pay it a higher compliment then that. It’s a terrific club with terrific support.”
Pulis added: “I’ve known Gary from my early days at Bristol Rovers when his dad Don gave me my debut and Gary would turn up to train as a 17-year-old.
“He’s been out of things for a while but that’s what attracted me in many ways – he’s fresh, he will hit the ground running and he’s a person I know I can bounce things off.”
Megson’s first competitive match back in the West Brom dugout will come at home to Bournemouth on August 12.