The 25-year-old defender ascended through Villa’s youth-team ranks to become a key member of the first team.
He said on the club’s official website: “I’m absolutely thrilled to sign a new contract. I’ve been at Aston Villa since I was a kid and I want to continue to play for this fantastic football club.
“Everyone is looking forward to the new season and I’m delighted to be going into the opening game on Saturday knowing my long-term future has been sorted.”
Manager Tim Sherwood said: “It’s great news. Ciaran wears his heart on his sleeve. You know what you’re going to get from Ciaran; he gives everything for the cause and that’s all you can ask for, as a manager.
“He was unfortunate with injuries last season, but he looks sharp now and we want to keep him fit. We’re pleased to have him here for a longer time.”
Sherwood expects to still be without Carles Gil (knock), Jack Grealish (hamstring) and Jores Okore (knee) for Saturday’s Premier League season-opener at Bournemouth.
“Carles and Jack are still out injured – they haven’t been able to do enough training, so it’s a disappointment,” said Sherwood
“Okore is still injured with his knee, which he had operated on at the end of last season.”
The meeting with the Cherries may come too soon.
Gil picked up a knock in last week’s friendly at Swindon while Grealish’s solitary pre-season outing came at Tamworth last Wednesday after a hamstring injury. Defender Okore is still recovering from knee surgery.
Though keen to acknowledge there are still two days of training before the big kick-off, Sherwood was more upbeat on his returning international players.