She was travelling in a red-colored Daihatsu car that caught fire after the collision, which also involved a black coloured Vauxhall Zafira car.
Police Scotland say the accident happened around 6 pm on Thursday on the busy trunk route, adjacent to North Cottage, Holywood, north of Dumfries.
The Daihatsu car was completely burned out as a result of the impact.
Police say neither the driver or front seat passenger in the Zafira car were injured.
The A76 was closed for several hours to allow an accident investigation to take place and diversions were put in place.
A spokesman at Dumfries said: “We are keen to hear from anyone who may have witnessed this collision and ask that they get in touch with police at Dumfries on telephone number 101.”
Scottish Fire and Rescue Service crews from Dumfries, Thornhill and Annan attended the incident.
The name of the woman who died is expected to be released later.