Although he will continue his playing career at Pertemps Bees, Cornwell has been retained by head coach Dean Ryan to help with the Academy - the breeding ground that has helped produce the likes of Ryan Lamb, Mark Foster, Olly Morgan and Jack Forster in recent seasons.
"For a place like Gloucester, links to its past players are one of the most important aspects in the fabric of the club and that is why we wanted to keep Mark involved," head coach Dean Ryan told www.gloucesterrugby.co.uk
"He had a wonderful career at Gloucester, is very well respected and could become a very good coach in the future.
"Last season, he captained our Guinness A League side with distinction and we didn't want to lose his influence around the club. He will take over from Mark Hewitt, who did a great job for us and has joined Cornish Pirates as forwards coach."
Cornwell (33) will work alongside Carl Hogg, who joined the club from Edinburgh Gunners last week.
"It's hard to explain but working in a sporting environment, particularly like the one at Gloucester, is unlike any other," Cornwell said. "I like to think I know how the players operate and I really enjoyed helping develop the youngsters in the Guinness A League last season.
"When the opportunity came about, the chance to stay at the club I know so well and have always been at was simply too good to turn down.
"The experiences of last season dragged something out of me I didn't previously know I possessed and I want to progress as far as I can as a coach."