The 28-year-old centre-back arrives on a straight season-long loan, with no option or obligation for Palace to buy him at the end of the campaign.
Disasi joined Chelsea in 2023 and has since had loan spells at Aston Villa and West Ham. He made 14 Premier League appearances for West Ham last season and has 58 top-flight appearances across his time with the three clubs.
The France international, who has five senior caps, remains under contract at Chelsea until 2029 but did not feature last season.
His arrival at Selhurst Park helps Palace strengthen their defence following the departure of Maxence Lacroix to Chelsea, with Disasi becoming the club's seventh signing of the transfer window.
Disasi said he was pleased to join a Palace side he believes is moving in the right direction.
"I'm very happy. The club has been going in a very good direction, so I think it was the right place for me to keep going," he said.
"I know that it's very tough to play against Palace at Selhurst Park - so I'm looking forward to being on the other side now."
Palace chairman Steve Parish also welcomed the defender's arrival.
"We are pleased welcome a defender of Axel's experience and calibre to Palace for the season. I look forward to seeing him in action at Selhurst Park," Parish said.
