The 21-year-old is delighted to continue his stay on the north-east coast having already made 93 appearances for the Dons.
He told the club's website: "When they indicated they were keen for me to commit to a new deal it really was an easy decision for me to put pen to paper."
Jack joined Aberdeen in 2010 and manager Derek McInnes added: "I'm thrilled another player has committed his future to the club for three years.
"I'm really looking forward to playing a part in Ryan's development.
"This is a strong statement from the club as we look to rebuild the squad and Ryan will be a very important player within that."