Hosokawa Tadatoshi (細川 忠利, December 21, 1586 – April 26, 1641) was a Japanese samurai daimyō of the early Edo period.

He was a patron of the martial artist Miyamoto Musashi.

Having studied the Yagyū Shinkage-ryū under Ujii Yashiro, Tadatoshi wanted his guest, Musashi, to fight against the sword master of his fief, and see which style was the strongest.

But Ujii, despite his full license in Yagyu Shinkage style, could not strike a single blow against him after numerous bouts.

In 1637, Tadatoshi and his son Hosokawa Mitsunao joined in the effort to subdue the Shimabara Rebellion, and fought with distinction.