Dorothea was born in Kaiserslautern, the only surviving child of the Count Palatine John Casimir of Simmern (1543–1592) from his marriage to Elisabeth (1552–1590), the daughter of Elector August of Saxony.

She married on 21 February 1595 in Heidelberg to Prince John George I of Anhalt-Dessau (1567–1618).

She was led to the altar by her guardian, Elector Palatine Frederick IV.

She was a member of the Virtuous Society under the nickname die Gastfreie ("the Hospitable").

Dorothea died in Sandersleben, aged 50, and was buried in the Church of St. Mary in Dessau.