The imposing centre-back, who scored 15 goals this season, already had two years left on his existing deal, meaning he will now stay at Ashton Gate until 2019.
“I’m delighted to sign an extension,” said Flint, who joined the Robins from Swindon for an undisclosed fee in 2013. “I’m tied down until 2019 and looking forward to the years ahead as a Bristol City player.
“I wouldn’t have dreamt of getting a contract extension at the start of last season, but I think it’s been a half-decent season personally for me and obviously a tremendous season for the club as a whole.
“I’m looking forward to testing myself in the Championship now.”
Boss Steve Cotterill praised Flint’s contribution and is hoping other players will now follow suit.
“Aden had already improved towards the end of the 2013/14 season but he stepped up another level last year,” Cotterill said.
“He’s composed on the ball and defends very well one against one. His heading ability we sometimes take for granted, but his goalscoring exploits only dried up when Matt Smith was in the team, funnily enough!
“He thoroughly deserves his new deal. Good, young defenders are hard to come by – particularly ones who can score goals like Aden.
“We’re delighted to have him under contract until 2019. Maybe one or two more will follow now.”