Albert Frederick was the second Duke of Prussia, serving in that capacity for more than five decades, into the 17th Century.

He was born on May 7, 1553, in Königsberg. His father was the first Duke of Prussia, Albert I, and his mother was Anna Marie of Brunswick-Lüneburg. He was his parents' only son and so grew up as the heir apparent to the duchy. He succeeded his father when the latter died, on March 20, 1568.

In 1573, Albert Frederick married Marie Eleonore of Cleves. They had seven children, six of whom lived into adulthood: Anna (1576), Marie (1579), Albert Frederick (1580), Sophie (1582), Eleanor (1583), and Magdalene (1586).

Prussia was beholden to the Kingdom of Poland, and the king at that time, Zygmunt August, was a cousin to Albert Frederick. The latter traded on that connection to the former in an attempt to join the Polish senate; he was unsuccessful. He also had some support to succeed his cousin on the Polish throne, when his cousin died, in 1572, but was unsuccessful in that endeavor as well.

The duke suffered from mental health issues throughout his marriage and submitted to three regents, who combined ruled for the largest part of the reign. In 1578, he submitted to the regency of a cousin, George Frederick of Brandenburg-Kulmbach; when he died, in 1603, Joachim Frederick took over; his death two years later brought the regency of his son, John Sigismund (also the duke's son-in-law), who was still serving when Albert Frederick himself died, on Aug. 27, 1618, in Fischhausen.