Born in Treptow an der Rega, today Trzebiatów, Poland, Frederick was the eldest son of Frederick II Eugene, Duke of Württemberg, and Sophia Dorothea of Brandenburg-Schwedt. Frederick's father was the third son of Charles Alexander, Duke of Württemberg, and Frederick was thus the nephew of the long-reigning duke Charles Eugene (). Since neither Duke Charles Eugene nor his next brother, Louis Eugene (), had any sons, it was expected that Frederick's father (also named Frederick) would eventually succeed to the Duchy, and would be succeeded in turn by Frederick.