Giacomini began his vocal career studying with Elena Ceriati, Marcello del Monaco and Vladimiro Badiali.
In 1974, Giacomini made his South American debut in Buenos Aires at the Teatro Colón as Pinkerton and Il tabarro.
This performance earned him several more contracts with the house in the big Italian repertory: Macbeth, Don Carlo, Il trovatore, Pagliacci and Tosca in the next few years.
He also sang for the Royal Family at the Covent Garden in 1988 and Mikhail Gorbachev in Moscow, took part in the historical staging of Aida set against the pyramids of Cairo in 1987 and was Calaf in Seoul on occasion of the opening of the Olympic Games in 1988.
Known colloquially as "Bepi", Giacomini continued to perform into his 60s, including a Cavaradossi in Tosca at the Royal Opera, Covent Garden.