Mizoguchi Naotoki (溝口直侯, June 11, 1778 – September 25, 1802) was the 9th daimyō of Shibata Domain in Echigo Province, Japan (modern-day Niigata Prefecture).

His mother was a daughter of Matsudaira Tadachika of Tatebayashi Domain.

Due to his youth, Naoyasu continued to rue the domain from retirement.

However, in 1789, the domain was ordered to exchange 20,000 koku of its territories in Echigo Province with an equivalent kokudaka of territory scattered widely across three districts of Mutsu Province.

Although the nominal kokudaka was the same, this discontiguous territories were remote, unimproved and this order was thus a tremendous financial burden on the domain.