He made his official opera debut there as Fléville in Andrea Chénier in April 1996, and subsequently appeared as Pâris in Roméo et Juliette (1996), Wagner in Faust (1997), Yamadori in Madama Butterfly (1997), and Moralès in Carmen (1997).
He went on to appear with the company as Fléville in Andrea Chenier, First Mate in Billy Budd, the title role of Hamlet, Sharpless in Madama Butterfly, Enrico Ashton in Lucia di Lammermoor, and Giorgio Germont in La traviata.
He made his San Francisco Opera debut as Dr. Falke in Die Fledermaus in 1996 and the following year appeared as Schaunard in La bohème and in the roles of Jack, Supervisor Kopp, and Stonewall Girl in the West Coast premiere of Stewart Wallace's opera Harvey Milk, based on the life of the San Francisco politician and gay rights activist Harvey Milk, who was assassinated in 1978.
He became a regular performer with the company, most notably as Count Almaviva in Le nozze di Figaro, Escamillo in Carmen, Doctor Malatesta in Don Pasquale, Belcore in L'elisir d'amore, Peter in Hansel and Gretel, Sharpless in the 2008 Emmy Award-winning Madama Butterfly, and Baron Scarpia in Tosca.
In Texas, he has performed with Austin Opera as Renato in Un Ballo in Maschera, Sharpless in Madame Butterfly, Giorgio Germont in La traviata, Iago in Otello, Rodrigo in Don Carlo, and the title role in Rigoletto.
In Latin America, Chioldi has appeared as Lord Dunmow in the South American premiere of Lennox Berkeley's A Dinner Engagement in São Paulo; as Iago in Otello with the Orquesta Filarmónica de Jalisco in Guadalajara; and as the baritone soloist in Mahler's Das Lied von der Erde at the Festival Internacional de Piano En Blanco & Negro in Mexico City.
His European appearances include Metifio in the concert performance and recording of Cilea's L'arlesiana at the Opéra National de Montpellier; Scarpia in Tosca with Ópera de Oviedo; Gerard in Andrea Chénier and Miller in Luisa Miller at the Gran Teatre del Liceu in Barcelona; the title role of Macbeth at the Teatro Verdi in Trieste; Marcello in La bohème at London's Royal Albert Hall; and the title role in Der fliegende Holländer at Pforzheim Opera in Germany.