After her father's accession to the throne in 1523 a marriage was suggested to the English claimant to the throne, Duke Richard of Suffolk, who was supported by King Francis of France, but without success.

In 1525, she received a proposal from the newly made Duke of Prussia.

The marriage was arranged by her father's German chancellor Wolfgang von Utenhof.

The wedding was conducted 12 February 1526 and Dorothea arrived with a large entourage in Königsberg in June.

Dorothea and her spouse corresponded with her brother, the king of Denmark, and acted as his political advisors.