Francesco Paolo Tosti received most of his music education in his native Ortona, Italy, as well as the conservatory in Naples. Tosti began his music education at the Royal College of San Pietro a Majella at the age of eleven. He studied violin with Pinto and composition with Saverio Mercadante, who became so impressed with Tosti that he appointed him student teacher, which afforded the young man a meagre salary of sixty francs a month. Poor health forced Tosti to leave his studies and return home to Ortona. He was confined to his bed for several months. During this time he composed several songs, two of which he submitted to the Florentine Art Society, and two others he submitted for publication to Ricordi. All four were rejected.

Once recovered from his illness, Tosti moved to Ancona, where his poverty was such that for weeks at a time he subsisted on nothing but oranges and stale bread. His travels brought him to Rome, where his fortunes turned. He met the pianist and composer Giovanni Sgambati, who became his patron. Sgambati arranged for Tosti to give a concert at the Sala Dante at which the Princess Margherita of Savoy (who later became Queen of Italy) was present. She was so impressed with his performance that she appointed him her singing professor. She later appointed him curator of the Musical Archives of Italy at the Court.

In 1875 Tosti traveled to London, England. He made several powerful friends who introduced him to the highest levels of English society. Tosti was a staple in fashionable drawing rooms and salons, and in 1880, he was made singing master to the Royal Family. His fame as a composer of songs grew rapidly while he was in England. One of his compositions, For Ever and For Ever was introduced by Violet Cameron at the Globe Theatre. This song became a favorite overnight, and there was an enormous demand for his compositions. By 1885 he was the most popular composer of songs in England. His publishers paid him a staggering retaining fee for twelve songs a year.

In 1894 Tosti joined the Royal Academy of Music as a professor. In 1906, he became a British citizen and was knighted two years later by his friend, King Edward VII. In 1913 he returned to Italy to spend his last years there. He died in Rome on December 2, 1916.

Tosti is remembered for his light, expressive songs, which are characterized by natural, singable melodies and sweet sentimentality. He is also known for his editions of Italian folk songs entitled "Canti popoliari Abruzzesi".

His style became very popular during the Belle Époque and is often known as salon music. His most famous works are Serenata (lyrics: Cesareo), Goodbye (lyrics: George J. Whyte Mellville) which is sometimes performed in Italian as Addio (lyrics: Rizzelli), and the popular Neapolitan song, Marechiare, the lyrics of which are by the prominent Neapolitan dialect poet, Salvatore Di Giacomo.

As a composer, Tosti is exceptional. Since the beginning of the recording era, numerous recording artists specializing in classical Italian repertoire have recorded Tosti songs, yet Tosti never composed opera. Notable examples on recording include Alessandro Moreschi (the only castrato who ever recorded) singing "Ideale", Nellie Melba singing "Mattinata" and Jussi Björling singing "L'alba separa dalla luce l'ombra".