After FUJIWARA no Nagate passed away in 771, Yoshitsugu became a central part of the Fujiwara family as a meritorious retainer of Emperor Konin's throne and was assigned as Naishin so occupied the next position of Daijokan (Grand Council of State) after ONAKATOMI no Kiyomaro.
宝亀2年（771年）藤原永手が死去すると光仁天皇擁立の功臣として藤原氏一門の中心的存在となり、内臣に任ぜられ、大中臣清麻呂に次いで、太政官の次席の座を占める。