His mother died shortly after his birth due to complications with the pregnancy, and both his grandfather and father followed during the same year, leaving the infant Chikamune as daimyō of Sendai.

In 1806, Chikamune was wed to Aya-hime's younger sister, Asa-hime, thus re-securing the connection between the Date clan and the Tokugawa, and in 1807, the retired rōjū Matsudaira Sadanobu spent four months in Sendai to oversee affairs.

In 1808, the shogunate assigned Sendai Domain to secure the northern frontier of Japan at Hakodate, Iturup and Kunashir against increasing incursions by Russia.

In 1809, Chikamune contracted smallpox, Although he survived the disease, he was left disfigured to the extent that his appearance at any official function was deemed inappropriate.

Sendai Domain had been in danger of attainder ever since the death of Date Narimura, and this had been avoided largely through a marriage tie with Shōgun Tokugawa Ienari.