Kellock has committed to the Warriors until May 2015, which includes options to keep playing as well as an ambassadorial role with the Warriors and the Scottish Rugby Union.
The 31-year-old former Scotland skipper joined Glasgow from Edinburgh in 2006 and made such an impression he was immediately named captain, a position he has retained in the seven seasons since.
The announcement comes as a boost ahead of Friday's 1872 Cup derby with Edinburgh in the first of a RaboDirect PRO12 double-header.
Kellock said: "It's a privilege to play for Glasgow Warriors and I'm honoured to be captain of this club. Over the next three or four years I have one goal and that's to help this club win silverware. There is a strong squad and work ethic here and I want to be at the forefront of the push for success.
"I'm still keen to develop as a player and learn from the coaches at Glasgow. I'm still working hard at my game, still trying to improve and I have more to give to the Warriors.
"We have been shaping up over the last two or three seasons to do something special for the game in Scotland and compete with the best teams in Europe. Winning a trophy against these sides is something I desperately want to happen for the game of rugby in Glasgow."
Glasgow head coach Gregor Townsend added: "Alastair embodies what the Warriors are all about and he will be one of the key drivers of our success in the years to come. Al is an outstanding leader and ambassador for the club, but it's his on-field performances that have earned him the reward of this contract extension.
"He is one of the best lineout forwards in the game right now and has been a major part of our strong scrummaging displays this year.
"Like any player in our squad there are areas he needs to keep working on to improve, but I've been impressed with his low tackling and ball-carrying this season. I'm delighted he has committed his future to the club."