He held office for a short period, from 13 August 1473 to 1 December 1474.

Born a member of the Marcello family, Nicolò was a trader with the Orient before he undertook various important public positions in the Republic of Venice such as provost of the Council of Ten, ducal councillor, and procurator of St Mark's.

Marcello married twice: first with Bianca Barbarigo and later with Contarina Contarini, with whom he had a daughter.

Upon his death, a funeral monument was designed by the artist Pietro Lombardo (c. 1435-1515) and erected in the Santa Marina church.

When the church was deconsecrated in 1818, the monument was moved to the Basilica dei Santi Giovanni e Paolo.