The Israel international has finalised a loan move to Selhurst Park and will stay until January.
Keinan was first-choice under Dave Jones last season, but since Malky Mackay's arrival in South Wales he has sunk down the pecking order - playing just once this term.
Keinan confirmed the move on Twitter saying: "Yeh! On loan to Crystal Palace for 6 weeks. Can't wait for the first game."