Ottaviano Querini is first attested in 1181, serving as either ducal councillor or judge in Venice.
[1] By 1200, he was back in Venice, where he served as ducal councillor under Doge Enrico Dandolo.
[1] In August 1205, he was in Venice, serving as one of the electors in the election of Pietro Ziani as doge.
[1] In April 1207, he was appointed as the Venetian Podestà of Constantinople, arriving in the city a month later.
[1] After the end of his tenure there, he returned to Venice, where he is last attested in September 1211, serving as a judge and witness to the charter granted to the Venetian military colonists on Crete.