Hosokawa Takakuni (細川 高国, 1484 – 17 July 1531) was the most powerful military commander in the Muromachi period under Ashikaga Yoshiharu, the twelfth shogun. His father was Hosokawa Masaharu, who was the branch of the Hosokawa clan.
In 1507, Hosokawa Masamoto was killed by his foster son, Hosokawa Sumiyuki who had been disinherited by Masamoto. Takakuni supported Hosokawa Sumimoto and got credit for putting down Sumiyuki. Because of that, he participated in the Muromachi shogunate in depth. In 1508, when Ōuchi Yoshioki marched his armies into Kyoto with Ashikaga Yoshiki (Ashikaga Yoshitane), the former shogun who had escaped to Suo Province, Takakuni conspired with them and purged the shogun Ashikaga Yoshizumi and Sumimoto to Ōmi Province.
Takakuni and Yoshioki took hold of the Muromachi shogunate. Takakuni took over as head of the Hosokawa people and took the blam of Kanrei. In addition, he also held the post of Shugo of Settsu Province, Tamba Province, Sanuki Province and Tosa Province. In 1518, he monopolized the powers of the shogunate after Yoshioki went back to his domain. In 1521, Yoshiki hated to be a puppet shogun, and escaped to Awa Province. Takakuni made Ashikaga Yoshiharu, son of Yoshizumi, take up the post of shogun.