Born into the prestigious noble house of Sanjo, he was active as a loyalist court noble in the Bakumatsu period. After the coup of August 18, 1863, he was expelled from Kyoto along with Choshu domain in the episode known as the Seven Nobles' Flight, and was placed under house arrest at Gojo and Dazaifu for about four years. This period of exile honed his thinking. After the Meiji Restoration he returned to the new government and in 1871 became Grand Minister of State, the head of government. Along with Iwakura Tomomi he anchored the inner core of the new government, and in the Korea debate he restrained hardliners such as Saigo and Itagaki and secured the priority of domestic governance. He tended to function more as a fair mediator than an able bureaucrat, bridging the strong personalities among Meiji government leaders. When the cabinet system was established in 1885 and Ito Hirobumi became the first Prime Minister, Sanjo became Lord Keeper of the Privy Seal. In his final years he served as an imperial advisor and died on February 18, 1891, at fifty-four.

Gentle and fair, he had the qualities of a mediator rather than a forceful politician. His noble birth endowed him with high culture and courtesy, and he served as a bridge between opposing factions.

As Grand Minister of State he stabilized the early Meiji government and established the priority of domestic governance. He is a symbolic figure among court-noble politicians who contributed to the formation of the modern Japanese state.