After her father's death Marie was raised in the Lutheran faith by her uncle George Frederick.

In 1546, Frederick finally adopted Lutheranism and assumed the administration of the Franconian territories from his brother-in-law Albert Alcibiades, Margrave of Brandenburg-Kulmbach.

Since their family was living in reduced circumstances, Marie repeatedly turned to her uncle Albert of Prussia for financial assistance.

As Electress, she was closely involved in governmental affairs, though Frederick tolerated no direct interference.

The Electress spent the last year of her life suffering from gout and was mostly confined to her bed.