Having assumed the post of Shogun, Ienari dismissed Okitsugu TANUMA, a dominant figure in the days of Ieharu, and made Sadanobu MATSUDAIRA chief the Roju (the senior councilors of the Tokugawa shogunate); Sadanobu was the renowned lord of the Shirakawa Domain in Mutsu Province, and was appointed at the recommendation of the Tokugawa Gosanke (the three privileged branches of the Tokugawa family).
将軍に就任すると、家治時代に権勢を振るった田沼意次を罷免し、代わって徳川御三家から推挙された陸奥白河藩主で名君の誉れ高かった松平定信を老中首座に任命した。