Kelly was born in Ireland on Christmas Day in the year 1762, six years after Mozart was born. His father, Thomas, was a Roman Catholic and felt that music was extremely important. So, when he was very young, Kelly was taught voice and piano. He proved to be a great singer.
For the Kellys, a great musician coming over as a guest was a regular occurance. In 1778, one particular guest, Venanzio Rauzzini, a great musician and friend of composer Joseph Haydn, recognized Kelly's talent and began to give him voice lessons. Kelly proved to have such great talent that Rauzzini suggested he be sent to a conservatory in Italy to study. Knowing how important music was (especially to his son), Thomas Kelly made plans immediately to send his son to Italy.
Before leaving, Kelly made his debut in Dublin, singing soprano as the Count in the opera, La buona figliuola.
In 1779, Kelly left for Italy and was enrolled at the 1537 Conservatorio Santa Maria di Loreto. In Italy, Kelly became known as both O'Kelly and Ochelli. Soon, he was performing for noblemen and women and even sang for the King and Queen of Naples.
In 1780, Kelly's voice matured and dropped to tenor, which gave him leading roles as tenor in operas. He travelled by boat to Livorno, where he met Nancy Storace, a 15-year-old soprano who would later play Susanna in the premier of Mozart's opera buffa, Le Nozze di Figaro (The Marriage of Figaro).
In 1783, Kelly accepted an invitation to begin working with an Italian company who worked for the Emporer Joseph II of the Holy Roman Empire in Vienna.
In Vienna, Kelly met court composer Antonio Salieri and starred in his opera Le scuola dei gelosi. He then went to visit Haydn in Eisenstadt. During his stay in Eisenstadt, Kelly met Mozart and his wife Constanze at a dinner--a friendship that would last until Mozart died.
Kelly wrote in his Reminicenses about Mozart; in fact, it is from him we get an idea of what Mozart looked like. He wrote,
"[Mozart was] a remarkably small man, very thin and pale, with a profusion of fine, fair hair of which he was rather vain."He went on to say that he often enjoyed playing billiards with Mozart (a favorite pastime of the Austrian composer) and never won.
In 1786, Kelly played Don Curzio in the premier of Mozart's Le Nozze di Figaro (The Marriage of Figaro).
In 1787, Kelly left for England to perform on Drury Lane (the street in the famous children's song, "Do You Know the Muffin Man?"). In 1788, he performed in Handel's Messiah.
In 1793, Kelly became acting manager of the Kings Theatre in London, after having already been principal English tenor at Drury Lane theatre from 1787 to 1789 (in 1789 the theatre had been closed and demolished).
Kelly later began composing, but as a career, it was not as successful for him as singing. He also opened up a music and wine shop, but the business unfortunately failed finacially. A friend once made him a humorous sign to hang above the shop that read, "Michael Kelly, Composer of Wines and Importer of Music".
Kelly died at the age of 64 in Margate. Most of what is known about him is found in his Reminicenses, which was published in 1826, although it is said that much of what Kelly wrote is in question. We do know, however, that he was friends with Mozart because of surviving letters from the composer to the singer.