The Republic of Ezo (蝦夷共和国 Ezo Kyōwakoku) was a short-lived breakaway state of Japan on the island now known as Hokkaido.

After the defeat of the forces of the Tokugawa Shogunate in the Boshin War (1868–1869), a part of the Shogun's navy led by Admiral Enomoto Takeaki fled to the northern island of Ezo, together with several thousand soldiers and a handful of French military advisors and their leader, Jules Brunet.

On December 25, 1868, they set up an independent Ezo Republic on the American model, and elected Enomoto as its president. These were the first elections ever held in Japan. They tried, in vain, to obtain international recognition for the new republic.

During the winter they fortified their defences around the southern peninsula of Hakodate, with the new fortress of Goryokaku at the center.

Imperial forces soon consolidated their hold on mainland Japan, and in April 1869 dispatched a fleet and an infantry force of 7,000 to Ezo. The Imperial forces progressed swiftly and won the Naval Battle of Hakodate, until the fortress of Goryokaku was surrounded with 800 remaining men. Enomoto decided to surrender on May 18, 1869, and accepted the Meiji Emperor's rule.

Enomoto was sentenced to a brief prison sentence, but was freed in 1872 and accepted a post as a government official in the newly renamed Hokkaido Land Agency. He later became ambassador to Russia, and held several ministry positions in the Meiji Government.