Jack was the subject of intense speculation towards the end of last season with only one year remaining on his deal at the time.
Those rumours were quashed when he signed an extension in May, keeping him at Pittodrie until the summer of 2017. Now his place in the Aberdeen squad has been cemented further with this honour.
Manager Derek McInnes said: “Ryan will relish the responsibility, he is the ideal choice.”
Jack led the team out in last night’s 8-2 victory in a friendly match with Brechin City.