The Spanish goalkeeper is widely regarded as one of the most talented shot-stoppers in European football, with his form this season reportedly drawing a host of interest.
However, the 27-year-old has revealed that he will not depart Espanyol in the summer.
"I have one year left of my contract and I always keep what I have signed," he told Mundo Deportivo.
"In addition, the renewal will be arranged. At Espanyol I am playing and enjoying it. Here I feel very comfortable and I have always said that I want to stay.
"I do not know much about the renewal nor do I want to know until it is all done. My role is to be focused on the job and contribute my bit to the team. I insist that I will play here next year."
Casilla came through the youth system at Real Madrid before moving to Espanyol in 2007.