安藝國
In 1522, he fought the Amago clan along with his father, Yoshioki, to win the control of Aki Province. Upon Yoshioki's death in 1528, Yoshitaka became the head of Ōuchi clan. In the 1530s, he led a military actions in the northern Kyūshū, defeating Shōni clan to win control of the area. With his back then secure, in 1540 he again started combating the Amago clan and by 1541, managed to completely control the Aki province.