He was a member of the Visconti family of Pisa, controlling Cagliari on behalf of his brother, who was judge jure uxoris from 1218.
Ubaldo's grandmother was Aligarda and his mother was a daughter of Torchitorio III of Cagliari, through whom he would have inherited some claim on the giudicato.
In mid-January 1213, William of Cagliari led the forces of Massa, Pistoia, the anti-Visconti faction in Pisa, and the militia of Guido Guerra III to victory near Massa over the forces of Lucca supported by the Visconti under Ubaldo, and by the deposed Pisan podestà Goffredo Musto.
In 1214, Lamberto and Ubaldo took the opportunity that year to launch an offensive at Cagliari and Arborea, but were beaten off by Comita and Genoa.
The war continued at sea, but was arrested by the entreaties of Pope Honorius III, who forced Comita to come to terms with Pisa (1 December 1217).