Geoffrey III, born , was the oldest son of Geoffrey II, Count of Gâtinais and Ermengarde-Blanche of Anjou. Ermengarde-Blanche was the daughter of Fulk III of Anjou. Both he and his younger brother Fulk, called "le Réchin", were raised at the court of their uncle, Geoffrey Martel. Both Geoffrey and Fulk were knighted by him in 1060. Geoffrey was well treated by his uncle but the count may have favored his younger nephew, Fulk. Nonetheless Geoffrey became his heir to succeed him as count of Anjou. Geoffrey III reigned as Count of Anjou until the was taken from him by his brother, Fulk.