Ings, who has been a revelation up front since his move to the Saints, had a year left on his deal but the move to Villa came as a surprise.
The 29-year-old, who has netted 41 times for Southampton, represents a shrewd acquisition for Dean Smith’s side, becoming the fourth arrival of the summer following Ashley Young, Emi Buendia and Leon Bailey.
"Danny is an outstanding Premier League footballer who has scored goals wherever he has played.” said manager Dean Smith.
“He is also a top professional with a great character who will be a leader in our squad and a role model for our rapidly developing young academy players who are now in and around the first team. I am delighted to welcome Danny to our great club” he added.