His elder brother, Raffaele (1782–1859) likewise trained under Giordani and had a career as a tenor appearing in the world premieres of Rossini's La scala di seta and L'inganno felice.
One of Monelli's earliest performances was in 1806 when he appeared with Raffaele in a production of Marcello Bernardini's Furberia e puntiglio at the Teatro della Concordia in Jesi.
[4] From 1818 through 1819 Monelli was in Barcelona as a member of the Teatre de la Santa Creu's Italian opera company directed by Pietro Generali.
His performances there included the leading tenor roles in three Rossini operas—La Cenerentola, Il barbiere di Siviglia, and La Gazza Ladra.
[5] On his return to Italy in 1820 he created the role of Nadir in the world premiere of Pacini's La schiava in Bagdad at the Teatro Carignano in Turin.