During his reign the tasks of government were carried out by a committee of court officials, because he devoted much of his time to hunting.

After instruction with local tutors during his early years, John Casimir studied with his cousin Christian II of Anhalt-Bernburg in Geneva from 1608 to 1609.

His tutors there were the Hofmeisters Markus Friedrich Wendelin and Peter von Sebottendorf.

In 1618, after the death of his father, John Casimir succeeded him in Anhalt-Dessau, but the tasks of government were carried out by a committee of court officials, because the new prince devoted much of his time to hunting.

During this time, in order to distract him, the famous poet and writer Philipp von Zesen was employed in his household.