Mizoguchi Nobunao (溝口宣直, 1605 – December 26, 1676) was the 3rd daimyō of Shibata Domain in Echigo Province, Japan (modern-day Niigata Prefecture).

Shortly afterwards, he was called upon by the shogunate to repair a portion of the ramparts of Edo Castle.

In 1633, the Agano River burst its banks and he was called upon to contract new dikes and flood control works.

He accompanied Shōgun Tokugawa Iemitsu on his trip to Kyoto and provided soldiers for enhanced security at Edo Castle during the Shimabara Rebellion.

Following the attainder of Katō Akinari from Aizu Domain in 1643, he was assigned to take possession of Aizuwakamatsu Castle on behalf of the shogunate.