Born in the Italian city of Milan, Cavalieri joined the Jesuits as a boy. He became interested in mathematics while studying Euclid's works and met Galileo, whose follower he became.

Cavalieri's fame rests chiefly on his work in geometry in which he paved the way for the development of the integral calculus by Isaac Newton and Gottfried Leibniz. In 1629 Cavalieri became professor of mathematics at Bologna, a post he held for the rest of his life. At Bologna he developed what he called his “method of indivisibles,” published in his Geometria indivisibilibus continuorum nova quadam ratione promota (1635; A Certain Method for the Development of a New Geometry of Continuous Indivisibles), which had much in common with the basic ideas of integral calculus.

Cavalieri also helped to popularize the use of logarithms in Italy through the publication of his Directorium generale uranometricum (1632; A General Directory of Uranometry).