Jack, who had one year left on his previous contract, committed his future to his hometown team until the summer of 2016. The 21-year-old, who has also played regularly at right-back, was called up to the Scotland squad for the victory over Croatia earlier this month and his continued commitment is a huge boost to McInnes.
Jack told RedTV: "The new manager said he would like to extend my contract and it's something I was looking to do as well. I was delighted with it.
"I know I have still got things to learn. The manager has assured me that he will help me achieve what I want to achieve and help my game along. I was delighted to hear that as well.
"Everyone is really excited about the new season, we have made a few signings and I think it could be a good season."
McInnes had previously extended top goalscorer Niall McGinn's contract and felt Jack's re-signing was another priority to complement the arrivals of former Celtic midfielders Willo Flood and Barry Robson and striker Calvin Zola from Burton.
McInnes said: "It's something we have been trying to move forward since the last couple of weeks of last season.
"We have been stung in the past by young players leaving the club and probably leaving too early. I can understand the temptation to go down south but the inclusion of Ryan in the Scotland squad will vindicate how well Ryan has done at Aberdeen.
"Ryan is certainly a player that is only going to get better. He is going to have to keep working hard and looking for that improvement in his game.
"He can play a number of positions but I do see midfield as the position he will predominately play. He is a good footballer, he is a great age, a good temperament and (has) a real steel and determination about him."
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