He was enormously admired within the field of opera for his rich and abundant voice, fine vocal technique and exceptional breath control.

He auditioned at a local opera house in 1949, where Luciano Donaggio (a retired singer beginning a second career as a teacher) heard him and urged him to study.

Cappuccilli was highly respected as a "Verdi baritone", where his beautiful voice, fine vocal technique, musical elegance and dignified stage presence were shown to their best advantage.

He left an impressive discography, he recorded Lucia di Lammermoor three times, first with Maria Callas in 1959, then with Margherita Guglielmi and finally with Beverly Sills in 1970.

He also recorded Don Carlo, Il trovatore and Aida under Herbert von Karajan Cappuccilli sang until his mid-sixties; an automobile accident in 1992 ended his stage career.