Borgioli was a quintessential tenore di grazia, with a smallish voice but great sweetness of timbre, an elegant but heartfelt delivery, and excellent technical facility. As was common performance practice, he added his own ornamentations to his bel canto roles, but, unlike many of his contemporaries, closely integrated these with the original lines while still showing off his own virtuosity. He was a particular favorite at La Scala and in England, where he was a regular at Glyndebourne, and at Covent Garden. Like many essentially lyric tenors, he prematurely sang heavier roles. This contributed to his vocal decline; nevertheless, he remained active in music as a teacher and administrator. He made his opera debut as Arturo in Bellini's I Puritani in 1914 at the Teatro Corso in Milan. In 1917, his performance as Fernando in Donizetti's La favorita at the Teatro dal Verme, conducted by Tullio Serafin, brought him to wide attention. The next year, he made his La Scala debut as Ernesto in Don Pasquale. His Covent Garden debut was in 1925 as Edgardo in Donizetti's Lucia di Lammermoor. In 1931, he made his Salzburg Festival debut as Almaviva in Rossini's The Barber of Seville, one of his most famous roles. During the '30s, he added heavier roles to his repertoire, including Cavaradossi, in Puccini's Tosca, and Don Jose, in Bizet's Carmen; while failing to elicit the enthusiastic response that his bel canto roles had inspired, these were still considered respectable performances. He began teaching in London, gradually reducing his singing appearances. Nevertheless, he made recordings into the early '40s. He was also artistic director at Cambridge Theater from 1946 until 1948.