Boss Jimmy Calderwood said: "Deciding whether to keep Mackie or not was always going to be one of the easiest I've made as a manager.
"It's made, now it is only a matter of sorting out the financial side and I don't anticipate any problems.
"He is one of the key players in the squad. He is Aberdeen-daft, he really does live the dream every time he pulls on the shirt. That's why I get baffled when some supporters have ago at him because he is one of them.
"He would do anything to help the team win. He's also a gem to work with and I want him at this club for as long as possible.
"His goal at Inverness was probably one of the best of his career and I was delighted to see him pass such a significant landmark.
"This season his touch has improved and his confidence is back. I'm sure he'll be an even bigger handful for defences in the second half of the season."