In 1179 when Jisho-sannen no Seihen (Rebellion of the third year of the Jisho era) took place, where Insei (rule by a Retired Emperor) by Emperor Goshirakawa was put to a halt and all the Anti-Taira nobles were ousted from the Imperial Court, Motomichi was designated as Naidaijin (minister), private audit, and Kampaku (chief adviser to the Emperor).
1179年、治承三年の政変で後白河天皇の院政が停止され反平家の公卿が一掃されると、11月には内大臣・内覧・関白に任じられた。