The 21-year-old, who has represented France at Under-21 level, finalised his deal with the Premier League side on Saturday.
Nice said in a statement on their official website: “An agreement was reached on Saturday for the transfer of Jordan Amavi to Aston Villa (Premier League).
“Jordan Amavi has not participated in the trip in Belgium on Friday to compete in the second friendly match of Aiglons. While his team-mates were on the road to Waregem, the young left-back (21) took the direction of England.
“And an agreement was made on Saturday afternoon with Aston Villa for the transfer.”
Nice did not confirm the length of Amavi’s contract nor the fee.