The Alfa Romeo Tipo B P3 was designed by Vittorio Jano and was Alfa Romeo's second monoposto (single seater) racer, the first being the Tipo A of 1931. Four Tipo A's had been constructed and none have survived; the closest Tipo A in existence is a replica which now resides in the Alfa Romeo Museum.

The Tipo A had been powered by two six-cylinder engines and matted to two gearboxes and dual propeller shafts. Though much of the design had carried over from the Tipo A, the Tipo B was equipped with a single eight-cylinder engine and drive-train in an effort to reduce the weight of the vehicle. The Tipo B made its inaugural appearance on June 5th, 1932 at the Monza Grand Prix. It was equipped with an eight-cylinder engine similar to the one Jano had created for the road-going 8C 2300. There were differences from the double overhead camshaft unit, such as the engines intake being mounted on the drivers left side. The engine capacity was larger due to an increase of stroke from 88 to 100 mm. Dual superchargers powered the front and rear testa fissa alloy blocks which resulted in nearly 200 horsepower. The single differential sat behind the three-speed gearbox. Power was sent to each rear wheels thanks to two propeller shafts designed in a triangular setup. These shafts ran beside the driver which allowed a lower sitting position and improved handling characteristics. 

At Monza, the Tipo B proved its potential by emerging victorious. In the hands of Tazio Nuvolari and Rudolf Caracciola, the Tipo B dominated the season with wins at the French and German Grand Prix's, among others. Part of its success was its excellent power-to-weight ratio. The body was constructed of aluminum and mechanical drums were used to keep the racer in the driver's control. 

The P3 was raced from 1932 through 1935 and provided many podium finishes for its drivers. In 1933 Alfa Romeo retired from racing and soon shifted the racing activities to Scuderia Ferrari. Ferrari's main driver was Tazio Nuvolari. Many of Tipo B cars were sold to privateers. Rule changes in 1934 meant the car was modified to accommodate the new regulations. One of the rules stated that the chassis was to be 33.5 inches wide, which meant the P3 was to be enlarged. 
As the years progressed, the car began to show its age. Competition was coming from teams such as Mercedes and Auto Union. Jano and Ferrari worked on improving the car throughout the years. In 1935, Nuvolari's car was given a larger engine, now having a bore of 71mm and a stroke of 100mm. This resulted in a displacement size of 3165cc and horsepower in the 265 neighborhood. Cantilever rear springs were adapted to improve upon the vehicles performance and handling. Later in the year, some of the Tipo B's were outfitted with hydraulic brakes and Dubonnet independent front suspension. 

Nuvolari's most famous and remembered race came in 1935 at the German Grand Prix. His car was now outclassed by the more powerful Mercedes and Auto Union cars. At the end of the race, it was Nuvolari in his Scuderia Ferrari Tipo B outpacing the rest of the competition and finishing in a very impressive and memorable first place.