Paoli was known as "The king of tenors" in his day. He was the first Puerto Rican to reach international fame in the arts at all. He showed an early interest in singing that was triggered by a concert performance by the Italian tenor, Pietro Bacceri in Ponce's Teatro La Perla. Paoli's parents were instrumental in supporting and guiding him during his youth but both of his parents died when he was only 12 years old. Paoli then went to live with his sister Amalia, who had moved to Spain. Paoli's sister Amalia helped arrange a scholarship from Spain's Queen María Cristina, for the young Paoli. In 1882, he started his studies under that scholarship, at the Real Monasterio del Escorial. He then went to study at the Academia de Canto La Scala in Milan, Italy in 1897, and subsequently debuted in Rossini's opera "William Tell", in Paris, only two years later. Paoli's great talent quickly brought him recognition and aclaim across Europe. By 1900, his performances had paved the way for a concert appearance at the pretigeous Covent Garden in London. Among his appearances were performances in the operas "Lohengrim" by Ricardo Wagner and Verdi's "Il Trovatore"; singing  for example, in cities such as Buenos Aires, St. Petersburg and Warsaw. He also appeared in countrues such as Egypt, Palestine, Hungary, Belgium, Cuba, Chile, Haiti, Colombia, Venezuela, Brazil, Canada, and the United States. In Moscow he was awarded a medaal by the Czar. Paoli was the first opera artist in the world to record an entire opera: Leoncavallo's "Clown", in 1907. It was the beginning of a highly successful career as a recording artist, giving him and his native Puerto Rico, world-wide recognition. Only three years later, Paoli was appointed "first tenor" by one of the best known opera companies in the world: La Scala, in Milan, Italy. In 1912, he again sang in the opera "Lohengrin" in Vienna and received a standing ovation from none other than the Austro-Hunagarian Emperor, Franz Joseph.In 1922 he started teaching voice in his native Puerto Rico, establishing a school together with his sister Amalia. His lot improved and he even helped produce the "Othello" at the Municipal Theater in San Juan shortly thereafter.