Bastianini was considered one of the finest Verdi and verismo voices of his day. His voice was naturally beautiful and he started his career in 1945 as a bass in a recital debut in Siena. His stage debut came later that year in Ravenna as Colline in Puccini's "La bohème." He later moved into the baritone range where he voice seemed better suited. His top notes thrilled audiences throughout his career for their ringing splendor. He made his debut as a baritone in Siena in January 1952 and later that year sang Tchaikovsky's Pique Dame at the Teatro Comunale in Florence. In 1953 he sang in Turin in Giordano's "Andrea Chenier" and Verdi's La traviata the Metropolitan Opera.
He was a regular at La Scala between 1954-1963 and the Vienna State Opera between 1958-1964. In the United States, he performed regularly at Metropolitan Opera between 1954-1957 and at the Lyric Opera of Chicago between 1955-1958. His last performance was in 1965 at the Metropolitan Opera.
He was buried in his hometown of Siena.