FILE – Moroccan defender Chadi Riad during a La Liga game with Real Betis. Photo: AFP
The 20-year-old centre-back, who spent last season on loan at Real Betis, has signed a deal with Palace until June 2029, subject to international clearance.
Riad, a full Morocco international with three caps, impressed during his loan spell at Betis, making 30 appearances in all competitions.
"I'm really happy to join Crystal Palace," Riad told the club's website. "The history of the club and the league were big factors in my decision.
"I've heard a lot about how the team played this year and I think it suits my style of play perfectly."
Born in Palma, Spain to Moroccan parents, Riad began his youth career with RCD Mallorca before joining Barcelona's La Masia academy.
"Chadi is an exciting young player who has already established himself at international level," said Palace chairman Steve Parish. "We are delighted to welcome him to the club."
Riad becomes Palace's first signing of the summer transfer window.
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