"Spektakel müssen sein" soll Kaiserin Maria Theresia 1759 zu ihrem Hoftheaterdirektor gesagt haben, ohne Spektakel "kann man nicht hier in einer solch großen Residenz bleiben". Dieser Devise trug man im 18. Jahrhundertnicht bloß am Kaiserhof sondern auch an den kleineren Residenzen Rechnung. Der Fürstenhof in Salzburg bot z. B. seinem Konzertmeiste. Michael Haydn vielfältigste Gelegenheiten, sein Können unter Beweis zu stellen: Hofbälle, Faschingsveranstaltungen, Universitätsfeiern, Theaterauführrungen.
Michael Haydn, like his brother, was a chorister at St Stephen's in Vienna. Shortly after leaving the choir-school, he was appointed Kapellmeister at Großwardein and later, in 1762, at Salzburg. The latter office he held for forty-three years, during which time he wrote over 360 compositions for the church and much instrumental music. He was an intimate friend of Mozart, who had a high opinion of his work, and the teacher of Carl Maria von Weber.
Michael Haydn's sacred choral works are generally regarded as being his most important, including the Missa Hispanica (which he exchanged for his diploma at Stockholm), a Mass in D minor, a Lauda Sion, and a set of graduals, forty-two of which are reprinted in Anton Diabelli's Ecciesiaslicon. He was also a prolific composer of secular music, including forty symphonies, a number of concerti and chamber music including a string quintet in C major which was once thought to have been by his brother Joseph.