Tadazane was the son of Ogasawara Hidemasa [ja] (1569–1615) with Toku-hime, daughter of Matsudaira Nobuyasu and granddaughter of Tokugawa Ieyasu. He married Kamehime, daughter of Honda Tadamasa with Kamehime (daughter of Matsudaira Nobuyasu) and adopted daughter of Tokugawa Ieyasu.^[1]

Following the deaths of his father and elder brother in the Osaka Summer Campaign, his holdings were transferred from Akashi Domain (100,000 koku) in Harima Province to the Kokura Domain (150,000 koku) Buzen Province.^{[citation needed]}

Famed as the lord who employed Miyamoto Musashi's adopted son Iori, Tadazane took part in the Shogunate's campaign to quell the Shimabara Rebellion, where the Kokura forces assisted in the execution of survivors of the rebel force, predominantly Christians.^{[citation needed]}

Tadazane's son Tadataka succeeded him. Other children included Nagayasu, Naganobu, Sanekata, and three daughters (one of them adopted from the Hachisuka clan of Tokushima-han).^{[citation needed]}

• Ogasawara clan