Ichiki graduated from the Tokyo Imperial University in 1887 and entered the Home Ministry the same year.
In 1890, he was sent to Germany for further studies, returning to Japan in 1894. From September 1907 through August 1918, he was appointed to one of the seats in the House of Peers in the Diet of Japan which were reserved for the Imperial Academy. From 1902-1906, Ichiki also served as Director-General of the Cabinet Legislation Bureau.
He served again in the same capacity from 1912-1913.
He first joined the Cabinet under the 2nd Ōkum administration in 1914 as Minister of Education. The following year, he was appointed Home Minister.
In 1925, Ichiki became Imperial Household Minister. From 1934 to 1936, Ichiki was chairman of the Privy Council.
This coincided with a period of considerable controversy over the role of the monarchy in Japan, especially centered around the works of Tatsukichi Minobe, a professor of constitutional law at Tokyo Imperial University and one of Ichiki’s former students.
After the assassination of former Prime Minister Saitō Makoto in the February 26 Incident in 1936, he held the post of Lord Keeper of the Privy Seal of Japan for 1 day only on 6 March 1936, as an interim measure, but was effectively forced into retirement by his political nemesis, Hiranuma Kiichirō. His grave is at the Yanaka Cemetery in Tokyo.
On his return, he became a professor of law at Tokyo Imperial University, and in 1906 became a member of the prestigious Imperial Academy.