An engraver, painter, and architect, Mezzanotte graduated in 1900 from the Istituto Superiore di Ingegneria, now the Politecnico, and began his career as a designer in the years immediately following. At the same time, he began exhibiting his etchings and paintings, a practice he continued until the 1940s. The Castello Sforzesco in Milan (Bertarelli Collection) houses the complete series of engravings produced up to 1939, architectural fantasies, and city views.
One of the leading architects active in Milan in the first half of the twentieth century, an exponent of Liberty and Milanese Neoclassicism, he gained fame among the general public primarily for his design of the Palazzo della Borsa in Milan, now known as Palazzo Mezzanotte, whose construction was completed in 1931.