The convertible sports car was due to be sold at British Car Auctions at Blackbushe to raise funds for the charity HopeHIV, which helps children who have lost their parents to AIDS.
The 1997 Aston Martin DB7 Volante automatic was donated anonymously. The car is finished in silver with a cream leather interior and has done 34,000 miles since leaving the factory. BCA valued it at around £40,000.
It was due to be sold with no reserve to the highest bidder during the regular Top Car auction.
All the proceeds will go direct to the charity, with BCA selling the vehicle free of charge.
Russell Davies, director of HopeHIV, said: "This is a wonderful gesture from an anonymous supporter of our work. We greatly appreciate BCA providing its expertise free to help us make the most from this generous donation.
"HopeHIV aims to support projects to help the 13 million children orphaned as the result of the HIV epidemic in sub-Saharan Africa. Many are living in communities where up to 40% of the adult population has contracted HIV."
BCA's Tim Naylor added: "We are delighted to help the charity maximise the value of this great donation. I am sure the money raised will be put to very good use indeed."