Breaking news: Villa sign Gueye
The 25-year-old Senegalese international has agreed a four-year deal with the club and joins from French side Lille for an undisclosed fee.
Gueye has represented his country on 24 occasions.
Manager Tim Sherwood said: "I'm really pleased to have brought Idrissa on board.
"He's been one of the best young midfielders in France for the last few seasons and there were a lot of teams trying to sign him this summer.
"I believe we are signing a player who is hungry to succeed, is entering what should be his best years and is perfectly suited to the Premier League."
Gueye will join up with the squad on receipt of his UK visa.