While in the army, he came to the notice of the conductor Antonino Votto, and subsequently studied with Ettore Campogalliani in Parma, Renato Pastorino in Milan and Valentino Metti in Piacenza.
In 1959, he sang at the New York City Opera as Calaf in Puccini's Turandot (conducted by Julius Rudel) and Rodolfo in La bohème (opposite Chester Ludgin as Marcello).
Labò was admired for his robust, typically Italianate voice, and his direct unaffected manner, other notable roles included Macduff in Verdi's Macbeth, Enzo in La Gioconda, and Turiddu in Mascagni's Cavalleria rusticana.
He made relatively few recordings, but can be heard in a complete Don Carlos, opposite Antonietta Stella, Ettore Bastianini, Boris Christoff, for Deutsche Grammophon, in 1960.
Among his "pirated" recordings is a 1958 performance of Aida in Mexico City, with Anita Cerquetti, Nell Rankin, Cornell MacNeil, Fernando Corena, and Norman Treigle.