The son of a doctor, he studied with Marc'Antonio Ingegneri (ca. 1547-92) at the cathedral in Cremona, obtaining a thorough grounding in traditional "Palestrina-style"   polyphony — the   lushsounding, rigorously constructed contrapuntal art of Palestrina and his circle. A precocious student, Monteverdi published several books of motets and madrigals in this conservative style before going to Mantua, in 1590 or 1591, to serve as a string instrumentalist at the court of Duke Vincenzo Gonzaga. There he came into contact with Giaches de Wert (1535-96), the master of the ducal chapel and a composer known for the daring, expressive use of chromaticism and dissonance in his madrigals. Wert's music would exert an important influence on Monteverdi, whose Third Book of madrigals, appearing in 1592, reveals a new boldness in approach and a much wider range of style.

In 1599 Monteverdi was passed over as Wert's successor in favor of the more experienced Benedetto Pallavicino, but in 1601, following Pallavicino's death, he was appointed maestro di cappella in Mantua.

Monteverdi's fame spread rapidly, supported by the publication of his Fourth Book of madrigals in 1603 and his Fifth Book in 1605. Even before the madrigals of the Fourth Book appeared in print, the conservative theorist Giovanni Maria Artusi—having heard some of them in private performance—published a fierce diatribe excoriating Monteverdi for his modernistic excesses. While Artusi's attack did nothing but enhance Monteverdi's stature as a madrigalist, it cried out for rebuttal. In 1607, when Monteverdi published his Scherzi musicali (Musical Jokes); a collection of part-songs for three voices, written in a much simpler style than the madrigals), he included a lengthy declaration (signed by his brother, Giulio Cesare Monteverdi, also a musician in the service of the Gonzaga family) arguing that his works utilized a new way of writing—a so-called seconda prattica, to which the rules of the old prima prattica, the method of Palestrina and the traditionalists, did not apply. The "second practice" was based on the premise that in vocal music, expression of the emotional content of the words was paramount and could justify the sorts of transgressions to which Artusi objected. The greatest achievement of Monteverdi's first 40 years was the completion, also in 1607, of his first opera, L'Orfeo, widely acknowledged as the first great work in the history of the genre. A second opera, Arianna, the music to which is now lost (except for one aria, "Lasciatemi morire"), followed in 1608.

Around this time Monteverdi became disenchanted with conditions at the Mantuan court. Feeling overworked and underappreciated, he retreated to the home of his father, Baldassare, in Cremona. But a petition written by Baldassare to Duke Vincenzo, seeking Claudio's release from the post of maestro di cappella, was rejected, and Monteverdi had no choice but to remain in the Gonzaga family's service until 1612— when, following Vincenzo's death, both he and his brother were sacked. The deteriorating conditions in Mantua had already prompted Monteverdi to begin looking elsewhere for employment, and undoubtedly played a part in his decision to publish, in 1610, a grand collection of church music, including a mass in the old style and a set of Vespers demonstrating his mastery of the new style (in its use of basso continuo, voices and instruments in combination, dance forms, virtuoso solo singing, and operatic declamation) alongside elements of the old (cantus firmus technique, divided choirs, and strict a cappella polyphony).

Monteverdi's dedication of the collection to Pope Paul V suggests he was hoping for an appointment in Rome, but, as things turned out, his future was in Venice. The death of Giulio Cesare Martinengo in July of 1613 left vacant the post of maestro di cappella at the Basilica of San Marco, the city's magnificent principal church, and on August 19, 1613, following his successful audition with a performance of one of his masses, Monteverdi got the job.Monteverdi would spend the remaining 30 years of his life in Venice. Much of the music he wrote for San Marco has been lost. A single retrospective volume of 40 sacred pieces was published in 1640, under the title Selva morale e spirituale (Moral and Spiritual Forest), with another, containing a mass and psalm settings, appearing posthumously in 1650. Three new books of madrigals were published during the composer's years in Venice. The Sixth Book, dating from 1614, is a collection of five-part settings, some coming fairly close to 16th-century style, others in the new soloistic manner known as the stile concertato, in which continuo instruments rather than voices fill out the texture.

In the latter, Monteverdi delights in showing how one or two voices can be more expressive than four or five. The Seventh Book of madrigals (1619), titled Concerto, consists mostly of duets and trios in this new style, while the Eighth Book (1638), titled Madrigali guerrieri, et amorosi (Warlike and Amorous Madrigals), runs the gamut from large-scale polyphonic works for voices and instruments to pieces in the theatrical style. A Ninth Book, consisting of miscellaneous madrigals and canzonettas, was published posthumously in 1651.