Built to comply with the championship’s new Group C regulations which were introduced in 1982, the car was a replacement for Porsche’s successful 936 model which competed in the previous Group 6 category of the World Championship. The project began in June 1981, and the first prototype chassis was completed on March 27, 1982, in time for the beginning of the World Championship season. Jürgen Barth tested the first chassis at Porsche’s private test track.

The 956 features a chassis made of an aluminium monocoque, a first for the company, helping to allow the car to meet the 800 kg (1764 lb) weight minimum in Group C. The engine is the same as the one used in the Porsche 936, the Type-935 2.65 L turbocharged Flat-6, producing approximately 635 hp (474 kW). A new 5-speed gearbox was also designed for the 956.

An improved chassis with better fuel efficiency from a Bosch Motronic electric system was developed for 1984, being termed the 956B. In total, twenty-eight 956s would be built by Porsche from 1982 to 1984, with an unofficial 29th chassis built from spare parts by Richard Lloyd Racing.

In 1983, 956 chassis #107 was used by Porsche as a testbed for their P01 Formula One engine, later badged as TAG and used by McLaren. The car was able to test some of the characteristics of a Formula One car in order to develop the engine.

The 956 would be officially replaced by the Porsche 962 in 1985, an evolution in the 956’s design.