The man, who was in his thirties, has not yet been named.
The accident happened shortly before 4am near Marton-cum-Grafton, on the B6265 which runs between Green Hammerton and Boroughbridge.
Emergency services went to the scene, but were unable to save the casualty.
The road has now been closed to allow the Collision Investigation Unit conduct a full and thorough investigation of the scene.
The road is expected to be closed for some time and motorists are advised to avoid the area.
A spokesperson for North Yorkshire Police said: "Anyone who was travelling along the B6265 at the time of the incident, or who has any information which would assist the investigation, is asked to dial 101 and pass the information to the Force Control Room. Please quote reference NYP-23092018-0089."