The defender joins Aston Villa from Real Betis in Seville in his native Spain, with whom he won the Copa del Rey last season.
Comfortable playing as either a left-sided full-back or in a more advanced position on the left flank, the 29-year-old has also played for Real Mallorca, CF Elche and Rayo Vallecano during his career to date.
Aston Villa head coach Unai Emery said, “Álex is a good player that can help our squad. He has been one of the top left-backs in La Liga over the past few seasons and we are delighted to have him here.”
Moreno’s move is subject to international clearance and a successful visa application.