In the year of his succession, he married Matilda la Gran Contessa, daughter of Boniface III of Tuscany, and Beatrice of Bar. By this marriage, he succeeded his father as margrave of Tuscany, for his father had been married to Beatrice of Bar, the mother of Matilda. From 1071, Godfrey lived separate from his wife. The two spouses were on opposite sides in the Investiture Controversy: Matilda was a partisan of Pope Gregory VII and Godfrey of the Emperor Henry IV.
He warred on Henry's behalf against Magnus, Duke of Saxony, in 1075 and on that of the bishop of Utrecht in 1076 against Dirk V of Holland and Robert I of Flanders. He was assassinated on the Scheldt on the eve of battle. His only child was a daughter, Beatrice, by Matilda. He nominated his nephew Godfrey of Bouillon to succeed him, but the emperor appointed his own son, Conrad. Godfrey of Bouillon succeeded eventually in 1087 and gained fame on the First Crusade.