The lock has decided to commit his future to Dave Rennie’s side, agreeing to a new deal which will keep him in Glasgow until 2020.
The 23-year-old has been at Scotstoun since signing his first professional contract in 2013 and helped them win the Pro12 title in 2015.
He’s made 39 appearances for Scotland as both he and brother Richie Gray have represented the national side.
Gray said: “This club is very special to me. It’s where I’m from, my family and my friends are here and it’s a city and a club that I love and I care about a lot. I’m very happy to be here and I’m proud to represent this city.”