King's first issue at the helm will be the magazine's 200th edition. He joins the title from Future Publishing.
"It's an honour to be joining such a prestigious, industry leading brand," King said. "I've long been an admirer of Play and I am looking forward to leading it into the future at a time when the PlayStation brand itself is also rocketing forward in the market."
Editor-in-chief Aaron Asadi added, "We are delighted to announce Ryan as Editor of one of our most treasured brands. A veteran of the industry and former Imagineer, Ryan's appointment is a real coup for the magazine. He has some fantastic ideas for the magazine and website and we can’t wait to see them come to fruition."
Play was launched in 1995 and is the UK's longest-running PlayStation-dedicated magazine. It is one of 20 regular print magazines published by Imagine Publishing.