Maria Anna Sophia of Saxony (Maria Anna Sophia Sabina Angela Franciska Xaveria; 29 August 1728 – 17 February 1797) was a daughter of King Augustus III of Poland and his wife Maria Josepha of Austria who became Electress of Bavaria by marriage to Maximilian III Joseph, Elector of Bavaria.

Maria Anna was married to her first cousin, the Bavarian Elector Maximilian III Joseph in 1747.

A secret treaty with Holy Roman Emperor Joseph II had been concluded in the end.

In exchange for Lower Bavaria, Charles Theodore was to receive the Austrian Netherlands (close to his ancestral domains), the Palatinate (already his patrimony), Jülich and Berg.

After her husband Maximilian III Joseph died, Maria Anna Sophia spent the rest of her life at Fürstenried Palace and enjoyed the gratitude of the Bavarian people and the heirs of the Zweibrücken-Birkenfeld branch: Charles II, Duke of Zweibrücken, and his brother Maximilian I Joseph of Bavaria, who finally succeeded Charles Theodore in 1799 as first King of Bavaria.