He was briefly adopted by the Tanegashima clan as an heir, but was returned to the Shimazu family while still a child. At age eight, he was adopted into the Shigetomi-Shimazu, a branch family of the main Shimazu house. Kanenoshin, now named Matajirō, came of age in 1828, and took the adult name Tadayuki (忠教). At age 22, following his marriage to the daughter of the previous Shigetomi lord, Tadakimi, he inherited family headship.
He was supported as a candidate for succession to the main Shimazu house during the Oyura Disturbance (お由羅騒動 Oyura sōdō). His half-brother Nariakira won the dispute and succeeded their father as lord of Satsuma; however, following Nariakira's death in 1858, Tadayuki's young son Mochihisa (later known as Tadayoshi) was chosen as the next lord of Satsuma. Tadayuki gained a position of primacy in Satsuma, due to his status as the lord's father. He returned to the main Shimazu house in 1861, and it was then that he changed his name to Hisamitsu.
In 1862, Hisamitsu went to Kyoto, and took part in the increasingly Kyoto-centered politics of the 1860s; he was a part of the kōbu-gattai political faction. It was during Hisamitsu's return from a stay in Edo, when three Englishmen on horseback offended his retainers by refusing to dismount or stand aside. Their failure to observe proper etiquette resulted in some argument, a chase, and one was killed, in what came to be known as the Namamugi Incident. Hisamitsu remained at the core of the kōbu-gattai movement in Kyoto, until Satsuma's secret alliance with men of Chōshu. He supported the Satsuma domain's military actions in the Boshin War, and retired soon after the Meiji Restoration. In the Meiji era, he was given the rank of prince (kōshaku (公爵)), the highest of the newly-created kazoku nobility and which was awarded for his clan's participation during the Restoration.
Hisamitsu died in 1887, at age 70. He is buried in Kagoshima Prefecture.