The Okazaki Domain encompassed the Mikawa Province, which is situated in what is now the eastern part of Aichi Prefecture.

The administrative center of the domain was established within the walls of the historic Okazaki Castle.

Due to its associations with Tokugawa Ieyasu, who was born in Okazaki Castle, the domain had a prestige greater than in its nominal valuation based on rice tax revenues.

After a defeat by the Imagawa clan in 1549, Ieyasu was taken hostage to Sunpu, but reclaimed Okazaki after the Battle of Okehazama in 1560.

Oda Nobunaga's execution of Matsudaira Nobuyasu in 1579 led to the Honda clan taking over Okazaki Castle, with Tanaka Yoshimasa enhancing its defenses.