Jack, whose father Garry played international rugby league for Australia, will now captain the Swans alongside Jarrad McVeigh.
It is a significant day for the Swans, with two players from Pennant Hills in Sydney's north west now given the responsibility of leading the premiers into the future.
"I think it's a good story for football in NSW," Swans coach John Longmire said.
"It's not the reason why we've done it, but it's great to have two local products like Jarrad and Kieren leading the football club.
"It's a great thing for the football club to have two local boys as co-captains."
It's a remarkable story for the 25-year-old Jack, who fought his way onto the club's rookie list back in 2005.
Making his debut two years later, he went on to win a club best and fairest in 2010 and bring up 100 games last season before helping lead the club to the premiership.
Jack joked he hadn't told his father of the decision, stating he would "find out now" watching a live telecast of the press conference, but he knew Garry would be extremely proud of his achievements.
The midfielder, who made the All Australian squad of 40 last season before narrowly missing out on the final team, was grateful for the opportunities given to him by the Swans.
"I'm obviously really honoured and humbled to receive this opportunity to co-captain with Jarrad," Jack said.
"It's a club that I've followed since I was a kid and they gave me an opportunity when a lot of clubs said I wasn't good enough.
"I'm looking forward to the challenges ahead."
Club games-record holder Goodes still believes there is plenty of football left in him, extending his contract until the end of the 2014 campaign.
But at a club camp in Coffs Harbour in January he said he "could tell it was the right time" to stand down, as some other leaders were ready to step up and carry the Swans forward.
"Everyone is probably wondering why and how I came to this decision and it's something that sits quite comfortably with me," he said.
"I'm very happy to step down as captain and I'm still going to drive the football club like I normally would.
"It was quite simple how easy it did feel. I didn't wrestle with it at all."
