Ōkubo Tadazane (大久保 忠真, 15 January 1782 – 4 April 1837) was the 7th daimyō of Odawara Domain in Sagami Province, (modern-day Kanagawa Prefecture) in mid-Edo period Japan.

Tadazane was born in Edo in 1782 (some sources state 1778) as the son of the 6th daimyō of Odawara, Ōkubo Tadaaki.

Four years later, on 28 January 1804, he was appointed to the concurrent position of Jisha-bugyō (Magistrate of Temples and Shrines).

As was usually the case with holders of the latter office, Tadazane became a Rōjū under the shōgun Tokugawa Ienari upon the completion of his duties in 1818 (having been recommended by Matsudaira Sadanobu).

Tadazane was married to a daughter of Hachisuka Haruaki, daimyō of Tokushima Domain, but his only son and heir Ōkubu Tadanaga died in 1831.