The 77-year-old was discovered by a member of the public in Hawick on Thursday morning.
He had been travelling on the road to Hathendean, near Knowetownhead Townhouse, when the vehicle overturned.
An ambulance was called but he was pronounced dead at the scene.
Sergeant John Easton said: “The man’s family have been informed and our condolences are with them at this sad time.
“Our enquiries continue to establish the full circumstances surrounding his death and we’d urge anyone who may have information which can help to get in touch as soon as possible.”
Anyone with information should contact the Road Policing Unit via 101, quoting incident number 1093 of November 9.