Fagerson, 25, is at the peak of his powers and is currently in South Africa as part of the British and Irish Lions squad preparing for the first Test.
Danny Wilson the Glasgow coach, described him as “world-class” and expressed his delight at tying him down on a new deal.
“It’s great to be able to retain someone of Zander’s calibre who has already gained international and British and Irish Lions honours, as well as becoming a club centurion all by the age of 25,” said Wilson.
“He is a world-class tighthead prop who has really kicked on these last few years. He’s an extremely effective scrummager who offers a huge amount in the loose as both an attacker and a defender.
“We’re excited about the direction in which this team is heading and Zander will play a big part in the club’s future. We look forward to continuing to work with him.”
Wilson will be hoping to see more of Fagerson in a Glasgow jersey in the new season after spending much of the last campaign without his Scotland caps due to the extended international autumn window and Covid restrictions.
Glasgow have not revealed the length of the new contract, describing it only as “long term”.
“I'm very happy to be continuing at Glasgow for the foreseeable future,” Fagerson told glasgowwarriors.org. “Glasgow is an incredibly special place for my family and I and it's become our home.
“I’m excited to keep developing as a player over the next couple of seasons and to help this team to achieve our potential, both individually and collectively. The signings Glasgow has made, both with coaches and players mean we have a very exciting future ahead of us both on and off the field.
“The culture and environment at Scotstoun is unlike anywhere else, it's a truly special club. I’d also like to thank Scottish Rugby for giving me the opportunity to continue to advance my career from within Scotland, and I'm going to continue to give my all for both club and country every time I'm selected.
“I can't wait to get back out and playing in front of our fans, who create an atmosphere that's right up there with the best in Europe. Hopefully it’s not too long before we can get the Warrior Nation back where they belong - in the stands in a sold-out Scotstoun.”
The 38-times capped Fagerson was a key player in Scotland’s 2021 Six Nations campaign, helping Gregor Townsend’s side secure notable away wins over England and France.
His form won him a call-up for the British and Irish Lions and he came off the bench against the Sigma Lions in the tour opener, becoming the seventh Glasgow Warriors player in the professional era to represent the touring side.
He then registered his first try in Lions colours in the victory over Stormers, coming off the bench to crash over from close-range in a 49-3 win.