The letter, which dates from Napoleon's ill-fated invasion of Russia, was bought by the Museum of Letters and Manuscripts in Paris.
It is written in code and was sold alongside a deciphered transcript.
It went under the hammer in Fontainebleau, south-east of Paris, at 10 times the initial estimate.
Before the auction, Jean Christophe Chataignier, director of the Osenat auction house, said the 1812 letter was expected to fetch between 10,000 and 15,000 euros.
It was written by Napoleon to Foreign Minister Hugues-Bernard Maret, who was at Vilnius in modern-day Lituania.
Having captured Moscow but with the Russian army having withdrawn and winter approaching, the emperor realised he had to turn back.
The first line reads: "On the 22nd at 3am I will be blowing up the Kremlin."
The letter also reveals Napoleon's frustration at the campaign, with his army ravaged by disease, cold and hunger: "My cavalry is in tatters, a lot of horses are dying. Make sure we buy more as soon as possible."
Napoleon kept the promise to blow up the Moscow Kremlin, destroying the Kremlin's walls and towers before retreating with his army, beginning a decline in his power that would lead to his abdication and exile just two years later.