The 6ft 2in, 18st 3lb tighthead has started in 41 of his 66 Premiership appearances for Harlequins and Warriors, having cut his teeth with Exeter Chiefs. He was an academy player at Ulster, as well as an age-grade and Ireland A internationalist, during now Alan Solomons' time with the province, and the chance to team up with the South African at Edinburgh was key to his decision to move north.
"I'm really excited about joining Edinburgh; it's a fantastic rugby club in a great city," said the 30-year-old. "I've just had a son so I'm looking forward to bringing him up in the city.
"I know how good a coach Alan Solomons is and what he brings to the table so I'm delighted to get a chance to work under his guidance again. He feels that the club has a good infrastructure in place and is now looking to build on it. I've earned a lot of experience in two very tough scrummaging leagues and I'm keen to be part of this vision to build a successful club and work with the younger guys and help them develop."
Solomons said: "John is well known to me from my time in Ulster when he was young boy playing under-20 rugby. He came through the age-grades in Ireland and then, in my opinion, did the right thing in signing for Exeter who were playing in the Championship.
"He is an outstanding scrummager, but is also good around the field. I think he will bring a lot to this club. We need depth in that tighthead position, and he'll give us a lot of experience in that role."