Albert became Duke of Prussia after paying feudal homage to his cousin, the King of Poland, Sigismund Augustus, on 19 July 1569 in Lublin.

Albert Frederick initially refused to recognize the election of Stefan Bathory and supported the candidacy of Maximilian of Austria.

He had twice tried to commit suicide and was prone to violent outbursts and held a great fear of " Turks and Muscovites " overrunning Germany.

[2] Albert Frederick was married in 1573 to Marie Eleonore of Cleves, a daughter of Wilhelm, Duke of Jülich-Cleves-Berg and Archduchess Maria of Austria (1531–1581).

Albert Frederick and Marie were parents to seven children: At his death, the duchy passed to his son-in-law John Sigismund, Margrave of Brandenburg, combining the two territories under a single dynasty and forming Brandenburg-Prussia.