The woman, who has yet to be formally identified, was found behind a Lidl store near Catterick yesterday afternoon (Wednesday).
North Yorkshire Police were called to the scene at Brough with St Giles at 16.45pm.
A 44-year-old man from North Yorkshire is being questioned in custody while extensive police enquiries continue in the area.
Anyone with information that could assist the investigation is urged to call North Yorkshire Police on 101, select option 1, and speak to the Force Control Room.
Alternatively, contact Crimestoppers anonymously on 0800 555111.
Please quote reference number 12190187139 when providing details about this incident.