Born in 1543, believed to be the brother (or illegitimate son) of Satomi Yoshihiro, 6th head of the Awa Satomi clan. After Yoshihiro's death, Yoshiyori prevailed in a succession dispute with Yoshihiro's son Umeomaru. In 1580 he conquered Kazusa Province and unified all Satomi domains, beginning construction of Tateyama Castle as the clan's new base that same year. He died in 1587 before its completion, leaving the task to his son Yoshiyasu.

Remembered as a lord who combined the political skill to win a succession dispute with the military success of unifying Kazusa Province. His death before completing his vision for Tateyama Castle speaks to unfinished ambition.

Tateyama Castle was completed under his son Yoshiyasu after Yoshiyori's death and became the Satomi clan's final stronghold. Though the Satomi were stripped of their domain in 1614 and the castle was demolished, the site is now preserved as Shiroyama Park, celebrated as the setting of the epic Nanso Satomi Hakkenden.