Hosokawa Tadatoshi (細川 忠利, December 21, 1586 – April 26, 1641) was a Japanese samurai daimyō of the early Edo period. He was the head of Kumamoto Domain. He was a patron of the martial artist Miyamoto Musashi. He married Chiyohime (1597–1649) daughter of Ogasawara Hidemasa and adopted daughter of the second Tokugawa shōgun, Hidetada. His childhood name was Mitsuchiyo (光千代). Tadatoshi's grave is in Kumamoto. His grandfather was Hosokawa Fujitaka.