After the Meiji Restoration, he was appointed among the first Directors-General of Foreign Affairs (外国事務総督), and served the fledgling government in early negotiations.

He served in the Imperial Court during his youth in the Bakumatsu period, participating in the sonnō jōi movement that advocated the overthrow of the shogunate and restoration of power to the emperor.

As the previous chairman, Nabeshima Naomasa, had resigned before beginning his work, it was Higashikuze who began the practical operation of the office.

In 1882, he served as Vice President of the Genrōin, and with the institution of the Kazoku peerage system in 1884, he was granted the title of count.

The hereditary status of the Higashikuze family would ordinarily have placed him as a viscount, but Michitomi's own achievements in the Meiji Restoration led him to be awarded a higher rank.