It is thought that the white Mini crashed off the road and went down an embankment. It was not discovered until daylight.
The accident happened some time between 02:00 and 07:30 on Saturday about two miles south of Langholm.
Police Scotland have appealed for anyone with information, or anyone who saw the car on Friday night, to contact them.
A man has died after his car crashed on the A7 in Dumfries and Galloway.