A product of the club’s youth academy, Jack wore the armband for the first time on Wednesday night and scored as Derek McInnes’ team defeated Brechin City 8-2 in a pre-season friendly.
He was perhaps a surprise choice ahead of Scotland squad defender Mark Reynolds, who retains the role he had as vice-captain when Anderson was still playing.
The 23-year-old impressed last season as Aberdeen recorded their highest league finish in 21 years with second place behind Premiership champions Celtic.
Jack scored three times in 42 appearances and was linked with a £1m summer move to Everton last month in the Scottish press.
The former Scotland U-21 international has one year of his current Pittodrie deal left and manager McInnes hopes having him leading the team on the park will allow him to excel.
He told Red TV: “Ryan will captain the team this season. With Russell retiring that responsibility had to fall on someone and I feel that Ryan will flourish under the responsibility of that role.
“I believe it will help his development as a player. He is a very influential player for us anyway and we are looking for that influence now as captain.
“It has to be said that when you consider who could have been your captain there were a number of players who came into my thoughts. Mark Reynolds will do what he has done for the last few years by supporting Jacko from the position of Vice-Captain. He is brilliant in that role.
“There are a few other players there who would make good captains. You want a team full of them but only one person can wear the arm band and this season it will be Ryan Jack.”