Luna, 22, who as a boy idolised Brazilian Roberto Carlos, agreed a three-year contract with the Birmingham club which escaped relegation last season thanks to a late surge in form, finishing 15th. He was an Under-20 international player.
He said in a club statement: "I've always believed that I could play in the Premier League and to have this opportunity with a club as historic and huge as Aston Villa - and with a manager who is building a squad of young players with great prospect - is tremendously exciting for me."
Manager Paul Lambert added Luna after previously signing Bulgarian midfielder Aleksandar Tonev, 23, Danish defender Jores Okore, 20, Dutch midfielder Leandro Bacuna, 21, and Danish striker Nicklas Helenius, 22.
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