The Scotland lock, 30, began his career with 47 games in a four-year spell at Warriors and is incoming head coach Danny Wilson's first signing.

Gray spent a season at Sale Sharks before three years at Castre and then a move to French Top 14 rivals Toulouse in 2016, winning the title last term.

"I can't wait to come back," he said.

"We were still at Firhill when I left and the club has made big moves forward since then. To come back and play at Scotstoun in front of my family and friends was a huge factor in my decision.

"I've learnt a lot and gained a lot of experience, and been part of a successful side over the last couple of years. I want to bring that experience back to Glasgow and win titles with the Warriors."

Wilson, who replaces Dave Rennie as Glasgow head coach next season, said that "passionate" Gray will be an "excellent addition".

Gray, who featured for the British and Irish Lions in the 2013 tour of Australia, won the last of his 65 Scotland caps against Italy in the 2018 Six Nations and opted out of selection for last year's World Cup.

A head injury made him unavailable for the Six Nations squad named by Gregor Townsend on Wednesday, but the head coach says he could still play a part in the tournament.