Emilio Villoresi was born in Milan, Italy, the younger brother of the star Maserati driver, Luigi Villoresi who co-piloted with him in several races at the beginning of their careers. Emilio Villoresi and his brother competed in the 1935 and 1936 Mille Miglia driving a Fiat 508CS Balilla Sport but after a disappointing finish they purchased a Maserati which they drove individually in different races. Emilio was so successful that he was signed to drive an Alfa Romeo for Scuderia Ferrari in the 1937 season.
Nicknamed "Mimì," at the 1937 Coppa Principessa di Piemonte, Emilio Villoresi earned a third place finish behind team-mates Giuseppe Farina and Clemente Biondetti and another third place at the inaugural "Circuito della Superba" at Genoa. In 1938, when the German Silver Arrows were dominating everything in Grand Prix events, Villoresi won the voiturette class at both the Coppa Ciano and the Italian Grand Prix. In May of 1939, he finished a strong third to the still dominant Mercedes-Benz cars of Hermann Lang and Rudolf Caracciola but his career was cut short the following month by his untimely death while testing an Alfa Romeo 158 Alfetta for Enzo Ferrari at the Autodromo Nazionale Monza.