He used the alias Niibori Matsusuke when he worked against the Shogun
Kido was born in Hagi, in Ch?sh? Domain (present-day Yamaguchi prefecture) as the latest son of Wada Masakage ,a samurai physician. He was adopted into the Katsura family at age seven, and until 1865 was known as Katsura Kogoro . He was educated at the academy of Yoshida Sh?in, from whom he adopted the philosophy of Imperial loyalism
In 1852, he went to Edo to study swordsmanship, established ties with radical samurai from Mito domain, learned artillery techniques with Egawa Tar?zaemon, and (after observing the construction of foreign ships in Nagasaki and Shimoda), returned to Ch?sh? to supervise the construction of the domain's first western-style warship
After 1858, Kido was based at the domain's Edo residence, where he served as liaison between the domain bureaucracy and radical elements among the young, lower-echelon Ch?sh? samurai who supported the Sonn? j?i movement. Coming under suspicion by the Shogunate for his ties with Mito loyalists after the attempted assassination of And? Nobumasa, he was transferred to Ky?to. However, while in Ky?to, he was unable to prevent the 30 September 1863 coup d'état by the forces of the Aizu and Satsuma domains, who drove the Ch?sh? forces out of the city. He was involved in the unsuccessful attempt by Ch?sh? to regain control of the city on 20 August 1864, and forced into hiding with a geisha by the name of Ikumatsu, who later became his wife.
After radical elements under Takasugi Shinsaku gained control of Ch?sh? politics, Kido was instrumental in establishing the Satch? Alliance which proved to be critical in the Boshin War and the subsequent Meiji Restoration.
Following the overthrow of the Tokugawa bakufu, Kido claimed a large role in the establishment of the new Meiji government. As a san'yo (Imperial Advisor) he helped draft the Five Charter Oath, and initiated policies of centralization and modernization. He helped direct the Abolition of the han system.
In 1871, he accompanied the Iwakura Mission on its round-the-world voyage to the United States and Europe, and was especially interested in western educational systems and politics. On his return to Japan, he became a strong advocate of the establishment of constitutional government. Realizing that Japan was not in any position to challenge the western powers in its present state, he also returned to Japan just in time to prevent an invasion of Korea ( Seikanron ).
Kido lost his dominant position in the Meiji oligarchy to ?kubo Toshimichi, and resigned from government in protest of the Taiwan Expedition of 1874, which he had strenuously opposed.
Following the Osaka Conference of 1875, Kido agreed to return to the government, and became chairman of the Assembly of Prefectural Governors that the ?saka Conference had created. He was also responsible for the education of the young Emperor Meiji.
During the middle of Satsuma Rebellion of 1877 he died of an illness that had been plaguing him for a long time already.
Kido's diary reveals an intense internal conflict between his loyalty to his home domain, Ch?sh?, and the greater interest of the country. He wrote often of having to fight rumors at home that he had betrayed his old friends; the idea of a nation was still relatively new in Japan and so the majority of samurai cared more for securing privileges for their own domain.
Together with Saig? Takamori and ?kubo Toshimichi, he is counted among what was known as the Ishin-no-Sanketsu , which means, roughly, "three great nobles of the restoration". His younger sister's grandson was Tokyo politician Kido K?ichi