The Jamaican defender, who sealed his permanent move to Selhurst Park on transfer deadline day, struggled with injuries while with Derby last season.
But Davis says he is now fully fit and ready to make his Eagles debut against Scunthorpe next weekend.
"I had knee surgery a year ago and missed pre-season so I was always playing catch up," he said.
"The injuries kept happening too but this season I have had a pre-season and feel good and my legs are fine. I am fit and ready to go."