Aoyama Tadakado served as a bushō during the Sengoku period.  He was a retainer of the Matsudaira clan of Mikawa Province.

In 1518, Tadakado was born as the lineal heir of Aoyama Tadayo, a retainer of the Matsudaira clan.

The Aoyama clan originated from Kōzuke Province.  In the era of Tadakado, the clan moved from Ōmi Province to the village of Dōdō in the Nukata District of Mikawa and served Matsudaira Hirotada.  Tadakado participated in the Second Battle of Azukizaka.  After the death of Hirotada, Tadakado served for a while under the command of Imagawa Yoshimoto.  In 1560, at the Battle of Okehazama, he served as a yoriki, or security officer, for Hirotada’s son, Matsudaira Motoyasu (later known as Tokugawa Ieyasu).  After the battle that resulted in the death of Yoshimoto, Tadakado served Motoyasu.  In 1563, during the Mikawa Ikkō-ikki, he joined the side of Motoyasu and defended Okazaki Castle.

The details of his demise are uncertain.  Under one theory, during the invasion of Mikawa by the Kai-Takeda clan in 1571, Tadakado made a meritorious defense, but later died of injuries sustained during the conflict and was fifty-four years old.  Alternatively, in 1575, he was killed during fighting against the Takeda clan and was sixty-five years old.

His son, Aoyama Tadanari, served the Tokugawa clan and ranked as a hereditary daimyō throughout the Edo period.