Andrews made his name at Ballymena in the 1990s, playing at lock and at number 8. He will begin his new job with Dungannon next month, having penned a two-year contract.
Part of Andrews' brief is that he will act as forwards coach to the Tyrone side, as well as being the team's head coach. Former Ireland international Jonny Bell is to continue as 'Gannon's assistant coach and backs coach.
"John Andrews arrives at Stevenson Park with a proven record as a coach for the last fives seasons with Rainey Old Boys rugby club, following a successful senior playing career at Ballymena," a Dungannon statement confirmed.
"He is a well-qualified coach, with Level Two IRFU accreditation, and was formerly IRFU Regional Development Manager in the North East of Ulster and Rugby Development Officer for Ulster Schools. He has wide experience in physical education and sports fitness training."
Meanwhile, Rainey Old Boys chairman Arnie McLean paid tribute to the role played by Andrews in the recent success of the Magherafelt-based club and wished him "every success in his future coaching career."
Rainey are now actively seeking a replacement player-coach.