The first Mil Milhas was organized by Eloy Gagliano and Wilson Fittipaldi Sr., the father of Wilson Fittipaldi Júnior and Emerson Fittipaldi. The two had been inspired by the 1949 Italian Mille Miglia. Wilson Fittipaldi Sr. was a journalist and brought media as well as sponsors such as auto parts companies to support the event. The first event was held on November 24–25, 1956 with 31 sports cars competing at the Interlagos circuit.
The Mil Milhas has been held nearly every year since its inception and is one of the longest running motor racing events in Brazil. Nearly every running has used the Interlagos circuit, but the 1997 and 1999 events were held at Jacarapagua and Curitiba respectively.