International prop commits to Warriors
Fagerson made his Glasgow Warriors debut from the bench against Benetton Treviso in Italy last season and since then has gone on to make 29 appearances for the club, scoring two tries.
He started Friday's 43-14 bonus-point win over Zebre in Parma, which moved the Warriors up to third in the PRO12.
The 20-year-old won his first cap for Scotland as a replacement in the 2016 Six Nations against England at Murrayfield in February and in doing so became the youngest prop to play for Scotland in half a century.
After coming through the BT Sport Scottish Rugby Academy system, the tighthead signed his first professional contract with the Warriors in March 2015, which was due to run until May 2017.
Fagerson, a product of the High School of Dundee and Strathallan, has represented Scotland at all age-grade levels and is the latest in a long line of players who have committed their futures to the Warriors this season.
Club captain Jonny Gray also put pen-to-paper on a new contract, along with Finn Russell, Pat MacArthur, Fraser Brown, Alex Allan, Sila Puafisi, Ali Price, Ryan Wilson, Rob Harley, Chris Fusaro and Peter Murchie. Props Jarrod Firth and Djustice Sears-Duru along with fly-half Rory Clegg joined the Warriors this season, while the club will welcome hooker Corey Flynn and winger Leonardo Sarto in the summer.
Speaking to glasgowwarriors.org, Zander Fagerson said: "I chose to sign for three years with Glasgow Warriors because I love the club and I feel we're going places.
"The club and Gregor (Townsend) have showed a lot of faith in me and I want to repay them for that.
"Glasgow Warriors is a club that strives to get better every day. Winning the PRO12 last season was a massive achievement and we're working hard to try and retain our title this year.
"I feel my game is coming along nicely and although I am nowhere near the finished article I'm continually growing and developing as a player.
"Working with Dan (McFarland) and being involved with Scotland has helped my scrummaging and the technical aspects of the game.
"I'm getting better with each game I play and I can't wait for the next three years."
Glasgow Warriors head coach Gregor Townsend said: "It's fantastic news for the club that Zander will be staying in Glasgow for at least another three years.
"He has worked really hard since making his debut for the club 18 months ago and getting capped for Scotland this year was another big milestone for him.
"It's important that we continue to retain the players who we feel can help the club improve and we look forward to Zander having a big role to play in the future."