Mozart Camargo Guarnieri (February 1, 1907 – January 13, 1993) was a Brazilian composer.

Guarnieri was born in Tietê, São Paulo. He studied piano, composition, and conducting in São Paulo and Paris. His compositions received significant recognition in the United States during the 1940s, leading to conducting opportunities in major American cities.

A key figure in the Brazilian national school, Guarnieri served as a conductor, a member of the Academia Brasileira de Música, and Director of the São Paulo Conservatório. His extensive oeuvre includes symphonies, concertos, operas, chamber music, piano pieces, and songs.

Regarded by some as the most important Brazilian composer after Heitor Villa-Lobos, Guarnieri was awarded the Gabriela Mistral Prize shortly before his death.