Hosokawa Mitsunao (細川 光尚, October 26, 1619 – January 28, 1650) was a Japanese daimyō of the early Edo period.

He was the grandson of the famous Christian convert (Kirishitan), Hosokawa Gracia.

Mitsunao was born in 1619, and was the eldest son of Hosokawa Tadatoshi.

In 1637, he joined his father in the effort to subdue the Shimabara Rebellion, and fought with distinction.

Mitsunao's suppression of the Abe family's revolt in 1642 is famous, due to its fictionalization by Mori Ōgai.