- Birth: 1512
- Death: 1585/8/29
- Sons: Itô Yoshimasu, Itô Suketaka
- Distinction: Lord of Hyûga province
- Japanese: 伊東義祐 (Itou Yoshisuke)
After some conflict against his uncle, Yoshisuke secured the succession, and succeeded his brother Sukemitsu as head of the Itô clan in 1533. He is said to have led the Itô clan to its greatest heights of power and prosperity. He developed strong connections with the capital, and was named to the Junior Third Rank in 1546. Yoshisuke also proved himself an able commander in various clashes with neighboring clans such as the Kitahara clan, while negotiating alliances with other clans such as the Kimotsuki. Yoshisuke managed to gain control of the port of Shibushi, in Hyûga, and gained some prominence in overseas trading.
However, at the same time, Yoshisuke contended with a number of rebellions among his retainers, and by 1568 he was on hostile terms with the Shimazu clan of Satsuma province. He took Obi castle in southern Hyûga in 1568, as well as the area of Masakiin (today, Ebino city), but lost both in 1572, when his 3,000-man army was defeated by 300 troops commanded by Shimazu Yoshihiro in the battle of Kizakibaru, which is sometimes called the "Okehazama of Kyushu." By this time Yoshisuke had reportedly allowed himself to sink into a luxuriant lifestyle like that of a Kyoto courtier and in this way has been compared to Imagawa Yoshimoto (who was killed at Okehazama); the defeat at Kizakibaru represented the beginning of the end for the Itô clan, however. Yoshisuke was defeated again at the battle of Takabaru in 1576. The following year, driven out of Hyûga by the Shimazu (who defeated him at the battle of Tozaki-Kamiya that year), he fled to the lands of the Ôtomo. He eventually retired to Kyoto after wandering the Inland Sea, and died in Sakai on 1585/8/29.