Magdalene Sibylle of Saxe-Weissenfels (3 September 1673 – 28 November 1726), was a German noblewoman member of the House of Wettin (Albertine line) and by marriage Duchess of Saxe-Eisenach.

Born in Halle, she was the oldest daughter and first child of Duke Johann Adolf I of Saxe-Weissenfels and his wife Johanna Magdalena, the daughter of Duke Frederick William II of Saxe-Altenburg.

She was named after her paternal great-grandmother, Duchess Magdalene Sibylle of Prussia.

In Weissenfels on 28 July 1708, Magdalene Sibylle married John William III, Duke of Saxe-Eisenach as his third wife.

They had three children, of whom only one survived to adulthood: She died in Eisenach aged 53 and was buried in the Georgenkirche, Eisenach.