Petronio moved the family to Venice in 1774, and his son worked with the father and a painter from Brescia called Lodovico Gallina.

After the Accademia Clementina was converted into the National Academy of Fine Arts in 1804, Fancelli joined but without a regular teaching appointment.

Over the years he collaborated in the decoration of palaces with a number of local artists including Vincenzo Martinelli,[3] Gaetano Caponeri, Bartolomeo Valiani, and Onofrio Zanotti.

He made curtains painted with mythological or historical themes, according to the taste of the time, for various theaters of Bologna (Communale, Contavalli, and Teatro del Corso) and that of Ascoli Piceno.

Among his works are a painting of the Stigmata of St Francis (1796) for the church of St Francis of Faenza; a painting of Saints Vincent Ferrer and Filippo Benizzi (1798) for San Giovanni in Persiceto; a Christ and the Maries and Crucifixion (1802) for the cycle of Mysteries of the Rosary in San Stefano in Bazzano.

Similar skills were used in works of scenic design for theatrical representations of Alessandro conquistatore della Persia (1820; Orloff, 1823; Giordani, 1855), and at the former Teatro Contavalli, the curtain depicting Marriage of Zeus and Hera; and theater of Corso, the Triumph of Sophocles.