A spokesperson for West Yorkshire Police confirmed they had been called at 7.46am by the ambulance service to reports that a man was having a suspected medical episode.
Officers attended the scene, on Nidd Drive, off Stansfield Road, where the man was pronounced dead.
Police are not treating the death as suspicious.
A police spokesperson said: "At 7.46 this morning police were called by the ambulance service to Nidd Drive in Castleford to reports a man was having a suspected medical episode.
"The man was pronounced dead a short while later.
"The death is not being treated as suspicious and a file is being prepared for the coroner."