Tokugawa Mitsusada (徳川 光貞, January 28, 1627 – September 25, 1705) was a daimyō in Japan during the Edo period (1603–1868). Mitsusada was born as the son and heir of Tokugawa Yorinobu and a grandson of Tokugawa Ieyasu with the childhood name Nagatomimaru (長福丸). Among his sons was the eighth Tokugawa shōgun Yoshimune. Norihime, a daughter of his, married Ichijō Kaneteru. He married the daughter of Prince Fushimi-no-Miya Sadakiyo, Yaso-no-Miya Teruko (who is also the sister of Asa no Miya Akiko who was 4th shōgun, Tokugawa Ietsuna's wife).
One of the gosanke, Mitsusada ruled the Wakayama Domain from its castle, his birthplace, in Wakayama. He reached the Junior Second court rank while alive, and was awarded the Junior First rank posthumously; he also held the ceremonial post of gon-dainagon. His grave is at Chōhō-ji in Wakayama. His other sons were Tokugawa Tsunanori (1665-1705) and Tokugawa Yoritomo (1680-1705).