Edouard joins for a reported £15million and becomes the Eagles' seventh arrival of this transfer window under Patrick Vieira.
The 23-year-old scored 86 goals in 179 appearances during his four-year stint at Celtic. His last game for the Scottish giants was Sunday's Old Firm derby, in which he missed a golden chance in a 1-0 defeat to rival Rangers.
A first word with Eddy 🤩— Crystal Palace F.C. (@CPFC) August 31, 2021
Odsonne Edouard speaks to Palace TV for the first time 🗣#CPFC
A former France youth international, he won three Scottish Premiership titles with the Hoops, as well as two Scottish Cups and two Scottish League Cups.
"I'm very happy to be here today," he told Palace's official club website.
"I can't [wait] to start to train with the team and to play for this club.
"Scoring goals in the Premier League may be the biggest challenge in my career.
"But I'm confident in myself and my team-mates to be successful."
Edouard arrives with Palace 14th in the Premier League having collected two points from their opening three games.
He could make his debut when the Eagles welcome to Tottenham to Selhurst Park on September 11.