Matsudaira Sadanobu (松平 定信, January 15, 1759 – June 14, 1829) was a Japanese daimyō of the mid-Edo period, famous for his financial reforms which saved the Shirakawa Domain, and the similar reforms he undertook during his tenure as chief senior councilor (老中首座, rōjū shuza) of the Tokugawa shogunate, from 1787 to 1793.