A first edition of Ian Fleming's Live and Let Die, which had been donated to the shop, raised almost 3,500 at auction.
The book was originally estimated to be worth around 800 but sold for more than four times that amount at Bonhams Auction House in Oxford, at the end of September.
Oxfam said it could spend the money on one of a number of things, such as setting up and maintaining a water supply for 3,800 people, or feeding 500 families emergency rations.
Alternatively, the charity could build two classrooms, train 50 farmers or build 70 toilets.
Staff came across the book among other donations in a black bin bag, and said they were delighted with the amount raised.
Oxfam Morningside bookshop manager Andy Crosby said: "Everyone at the shop was eager to see how much the book would be auctioned for. I didn't think that it would raise so much money and I am thrilled that it did.
"It is not every day you manage to raise such an amount from the sale of one book, and the money will help to make a real difference to Oxfam's programmes."