Born into a low-ranking samurai family in Kagoshima, Satsuma Domain (present-day Kagoshima city). He fought for the Satsuma clan in the Boshin War of 1868, then went to England on government orders to study (1871–1878). Returning to Japan he entered the navy, and in the First Sino-Japanese War (1894–1895) served as captain of the Naniwa, making the legally complex decision to sink the Kowshing — a British-flagged transport carrying Chinese troops. Appointed Commander-in-Chief of the Combined Fleet in 1903, he directed the surprise attack on Port Arthur (Ryojun) at the outbreak of the Russo-Japanese War. In May 1905 at the Battle of Tsushima he met the Russian Baltic Fleet with the famous "T-crossing" maneuver and achieved a complete victory unprecedented in naval history. The triumph caused a worldwide sensation, and Togo was hailed in Europe and America as "the greatest admiral since Nelson." After the Portsmouth Peace Treaty he held posts including Chief of the Naval General Staff, and was promoted to Fleet Admiral in 1913. In his later years he served as a tutor to Emperor Showa. He died in Tokyo in 1934 at age 87.

Taciturn, humble, and stoic — a model warrior who never displayed emotion. Though called the "Nelson of the East," he consistently attributed all praise to his officers and the fleet as a whole. He combined calm situational judgment with bold decisiveness, and his commanding presence on the flagship Mikasa at the Battle of Tsushima has become legendary to posterity.

The overwhelming victory at Tsushima sent shockwaves through the world as the moment a small Asian nation defeated a great Western power, influencing nationalist movements across Asia. The flagship Mikasa is preserved and exhibited in Yokosuka, drawing many visitors as a naval memorial. Togo is enshrined as a deity at Togo Shrine in Harajuku, Tokyo, where he is still venerated.