Mizoguchi Nobukatsu (溝口宣勝, 1582 – November 24, 1628) was a Sengoku period samurai and the 2nd daimyō of Shibata Domain in early Edo period Echigo Province, Japan (modern-day Niigata Prefecture).

His childhood name was Hisasaburō (久三郎), but he changed it to Hidenobu (秀信) after he entered into the service of Toyotomi Hideyoshi in 1597.

After the establishment of the Tokugawa shogunate, the clan was confirmed in its holding of Shibata Domain.

Yoshikatsu already had 5000 koku which he had received from his father directly, but returned these lands to Nobukatsu, as his elder brother would have more expenses in his duties to the shogunate while serving in Edo.

Nobukatsu made much efforts in increasing the rice production of his domain, and although he increased the kokudaka by 15,000 koku, he gave all of these new lands to sons of his younger brothers, keeping Shibata Domain itself at 50,000 koku.