Valpert was patriarch from 874 to 900 ca. In 875 he made an assault to the island of Grado.
In April 877 pope John VIII sent him a letter, which was also addressed to John archbishop of Ravenna and Ansperto Confalonieri archbishop of Milano, about the excommunication of Adalard, bishop of Verona. In 880 Valpert assaulted Grado for a second time; the doge Orso Partecipazio was able to settle the situation without rushing to arms: in exchange for the peace with the Church of Grado, Venice granted the patriarch freedom of trading and the opening of a new port, Venetian traders being exempted by all taxes in all the territory of the Patriarchate. Under this agreement the two churches of Aquileia and Grado lived in peace for a sixty years. Later on Valpert accompanied Charles the Fat to Rome for his coronation as emperor and king of Italy.
Valpert is mentioned for the year 882, because he supported the theses of Photios, patriarch of Constantinople, which were critical towards the Roman church and the primacy of the bishop of Rome. In that same year he consecrated St. Leonardo’s church at Cavalicco. As a patriarch of Aquileia, Valpert had also jurisdiction over lands where Slavs had recently penetrated, and he is mentioned for having ordained a Croatian priest, Theodosios of Nona, bishop of that church.