As Lord Keeper of the Privy Seal of Japan, Makino served as Emperor Hirohito's chief counselor on the monarch's position in Japanese society and policymaking.

After victory in World War I, Makino was appointed to be one of Japan's ambassador plenipotentiaries to the Paris Peace Conference of 1919, headed by the elder statesman, Marquis Saionji.

In 1871, at age 11, he accompanied Ōkubo on the Iwakura Mission to the United States as a student, and briefly attended school in Philadelphia.

Over the course of his political career, he aligned his policies closely with Itō Hirobumi and later, with Saionji, and was considered one of the early leaders of the Liberalism movement in Japan.

[4] After victory in World War I, Makino was appointed to be one of Japan's ambassador plenipotentiaries to the Paris Peace Conference of 1919, headed by the elder statesman, Marquis Saionji.

Behind the scenes, he strove to improve Anglo-Japanese and Japanese-American relations, and he shared Saionji Kinmochi's efforts to shield the Emperor from direct involvement in political affairs.

Some historians point to this as having the unforeseen effect of making the Emperor reluctant to curb the trend towards militarism.

Although he formally retired his positions in 1935, his relations with Hirohito remained good, and he still had much power and influence behind the scenes.

After the war, his reputation as an "old liberalist" gave him high credibility, and the politician Ichirō Hatoyama attempted to recruit him to the Liberal Party as its chairman.