Miura Sadahiro served as a bushō during the Sengoku period. He was also known as Noto-no-kami.
Sadahiro was born as the eldest son of Miura Sadahisa based in Mimasaka Province. His younger brother was Miura Sadakatsu.
After the death of his father on 9/16 of Tenbun 17 (1548), Sadahiro inherited the headship of the clan. Thereafter, as the main heir to the family, he served under the Amago clan of Izumo Province, but later returned to Mimasaka. Together with Maki Naoharu and others, Sadahiro aimed to revive the Miura clan which had collapsed following an invasion of Mimasaka by Mimura Iechika, a daimyō based in Bitchū Province.
In the second month of 1566, while engaging in deliberations with his senior retainers at the Kōzen Temple in the village of Momi in Mimasaka, Iechika was shot and killed by matchlocks wielded by Endō Hidekiyo and his brother, Endō Toshimichi, ordered by Ukita Naoie. At the time, this marked a rare assassination by firearms. Sadahiro took advantage of this opportunity to recapture his landholdings.
On 2/19 of Eiroku 11 (1568), Sadahiro was attacked by Mōri Motonari, leading to the death of his uncle, Miura Sadamori. In addition, the Mōri army toppled Sadahiro’s base at Katsuyama Castle and, once again, he was ousted from his territory. In 1570, Sadahiro recovered his territory with the support of Yamanaka Yukimori, a retainer of the Amago clan and leader of the Amago Revival Army.
In 1574, when Uragami Munekage and Ukita Naoie came into conflict, Sadahiro aligned with the Uragami clan and brought into the alliance Mimura Motochika (Iechika’s second son and heir) of Bitchū. This led to clashes against the Ukita clan and, in 1575, an invasion by the Mōri following their pacification of Bitchū. In the ninth month, Sadahiro surrendered to Ukita Naoie after the Siege of Tenjinayama Castle.
In 1582, Sadahiro participated in the Battle of Bitchū-Takamatsu. He later died of illness in Hayashida in Harima Province.