Yixin (1833-1898), an imperial prince of the Aisin Gioro clan, was the sixth son of Emperor Daoguang (r. 1821-1850) and the half-brother of Emperor Xianfeng (r. 1851-1861). In 1851, Yixin was appointed as Qinwang (prince of the first rank) or Prince Kung of the first rank. In 1853, Yixin was in charge of defending affairs in Beijing. In 1854, he was appointed as Dutong (Banner commander), Youzongzheng (Right Head of the Imperial Clan Court), and Zongling (Head of the Imperial Clan Court). In 1855, Yixin was removed from all posts because he claimed the title of Queen for his dead mother. In 1857, he was reestablished as a Dutong. In 1859, he was appointed the Minister of the Interior.
In 1860, as Anglo-French forces approached the capital Beijing, Yixin negotiated with the British, French and Russians, and signed the Convention of Peking on behalf of the Qing Empire.
Yixin became the main interlocutor of the Western powers and was in charge of executing matters arising under the Convention of Peking. In the same year, Yixin founded the Zongli Yamen to deal with diplomatic issues with foreign countries, which was the first of its kind in modern China.
After Xianfeng's death in 1861, Yixin arranged the Xinyou Coup together with the Empress Dowager Cixi (Emperor Xianfeng's concubine) and Ci'an (Emperor Xianfeng's wife). Through this coup, Yixin and his allies removed from power the eight regents that Emperor Xianfeng had appointed on his deathbed to ensure the succession of his only son, Emperor Tongzhi (r. 1862-1874).
After the coup, Yixin was appointed Prince Regent. His great influence caused the misgivings of the Empress Dowager Cixi, who managed to demote him in 1865, accusing him of corruption and lack of respect for the emperor.
In 1894, Empress Dowager Cixi summoned Yixin back to the imperial court, put him back in charge of the Zongli Yamen and commissioned him to oversee the Beiyang Fleet (the Qing Navy) and military affairs. In 1898, Yixin died at 67 and was buried at the foot of Cuihua Mountain in Changping, Beijing. The emperor Guangxu (r. 1875-1908) granted him the posthumous name Zhong (literally "loyal").