When the Heiji War broke out in 1159, his brother Korekata once took part in the rebel army of FUJIWARA no Nobuyori and then switched sides, but Nariyori's action was coolheaded from start to finish, so he enabled the Retired Emperor Goshirakawa to escape from Dairi (the Inner Palace).
平治元年(1159年)の平治の乱に際しては、兄の惟方が藤原信頼の叛乱軍に一旦加担しながら寝返るという動きを見せる中、成頼は終始冷静に行動し、後白河上皇を内裏から無事に脱出させる。