Claudio Merlotti Latinized his name to Merulo (the original Italian form means blackbirds and Merulo is the Latin version). He is not related to Tarquinio Merula (ca. 1595-1665), but Jacinto Merulo (1595-1650), a minor composer of Parma, may have been a grandnephew. He studied with Tuttovale Menon (an expatriate French composer/teacher) and Girolamo Donato. He became organist of Brescia Cathedral in 1556, signing a five-year contract. Nevertheless, when the post of organist of St Mark's in Venice opened up in 1557, he competed for the position and won it, beating out Andrea Gabrieli, among others.
His reputation as a brilliant organist spread quickly and he initiated a series of Sunday afternoon concerts in the basilica. He was highly regarded by the church and the Doge, which rewarded him with regular pay increases. He remained there for 30 years. During that period, he established a printing and publishing business, issuing his own music and books of madrigals by Philippe Verdelot, Costanzo Festa, and others. He was entrusted with composing the music for some of the most important events of his time, including the state visit of Henry III of France in 1574 and the marriage of Francesca de' Medici and Bianca Cappello in Florence in 1589.
Unexpectedly, he left Venice in 1584. The next solid evidence of his whereabouts shows that by 1586, he had been hired as organist to the Duke of Parma; it is likely that at some point before then he worked for the Duke of Mantua. In 1587, he added the job of organist of the Parma cathedral to his post with the Duke. If he had left Venice to improve his position, he succeeded. He added a third post in 1591, as organist to the wealthy Steccata family.
He remained famous for his skills as an organist and was widely regarded as the best player of his age. He was a skilled teacher and a thoughtful student of keyboard technique. He studied the actions of the finger and codified exercises intended to give fluidity and evenness among the fingers, an important development in keyboard technique.
On April 25, 1604, Merulo woke up with a sharp pain in his lower abdomen. The symptoms that were recorded describe a classic case of appendicitis and ensuing peritonitis. He died after a week of great pain. He was buried in Parma Cathedral next to the composer Cipriano de Rore after the honor of a state funeral.
Merulo typified the growth of instrumental music during the late Renaissance. He developed a personal keyboard style, basing his melodies on vocal music. He invented new approaches to embellish melodies that lifted this from a set of mechanical and predictable formulas to a much more artistic part of keyboard performing. He even used written-out ornaments as formal devices: by repeating one ornament, especially devised for a particular piece, he added unity to it. He built pieces on an alternation of rather formal counterpoint with passages giving the impression of improvisation and a chance to display virtuosity in performance. This virtuoso spirit is quite unusual for his age. Wild flights in one hand against held chords in the other, free dissonance sometimes ignoring rules of voice leading, and other effects are sometimes astonishingly anticipating the mood of the Romantic era. His innovations were a principal source of the keyboard style of the Baroque. In addition, he wrote some very good motets and madrigals.