Viscount Matsudaira Tadakazu (松平 忠和, September 14, 1851 – June 8, 1917) was the 8th and final daimyō of Shimabara Domain in Hizen Province, Kyūshū, Japan (modern-day Nagasaki Prefecture).

In 1861, when the 7th daimyō of Shimabara, Matsudaira Tadachika died without heir, Tadakazu was selected as his replacement, and was posthumously adopted as his son.

In 1868, with the start of the Boshin War, he pledged Shimabara domain in support of Emperor Meiji, and proved his loyalty by committing his troops to the northern campaign against the Ōuetsu Reppan Dōmei, fighting at Akita and Morioka.

He later served as chief priest of Nikkō Tōshō-gū in the Meiji period; he was also created viscount (shishaku) under the kazoku peerage system.

Matsudaira Tadakazu died in June 1917, and his grave is at the temple of Honko-ji in Kōta, Aichi.