Iwakura Tomomi was born as the second child of Hofadligen Horikawa Yasuchika and adopted by Iwakura Tomoyasu.
At the imperial court, he worked in the decline phase of the shogunate. But He was in the eighth month of 1862, inter alia, for his involvement in the marriage of Princess Kazu no Miya to Tokugawa Iemochi in disgrace and temporarily lost his power. Through his contact with low asked priests in some of the hochrangigeren shrines in Kyoto he remained, however, during which the political situation well informed.
In January 1867 the Emperor Komei allegedly murdered Iwakura, because it was received on the policy of rapprochement towards the Shogunate. In the same year he propagated along with several scholars of Kokugaku ( including Gonda Naosuke and Ochiai Naoaki ) the integration of Shinto elements in the anti- Bakufu movement and participated in this way to the Meiji Restoration. He received in 1871 the Meiji government the post of Udaijin and as foreign minister (外务 卿, Gaimu - kyō ).
From 1871 to 1873 headed the Iwakura named after him Iwakura Mission to Europe and the United States, whose aim was the unequal treaties that were forced upon Japan to dissolve and to discover Europe for the Japanese. The first goal was not achieved, however, he brought a lot of new technology back to Japan.
On December 18, 1882 Iwakura received a high-level post in the Kunaishō, from which he tried to have included several articles on institutional entanglement of Shinto and Tennō in the Meiji Constitution.