He served in a number of important government and military posts, including member of the Central Military Commission, Political Commissar of the Beijing Military Region, and Vice Premier of the State Council.
After Mao's death in 1976, he supported Mao's designated successor, Hua Guofeng, in purging the Gang of Four.
Two years later, Deng Xiaoping ousted Hua from his leadership position, and Ji, labelled the "Little Gang of Four" together with other prominent Hua supporters, was forced out of politics.