Teresa Boni Benelli established the company in Pesaro in 1911 after the death of her husband, investing the family capital in a business that would provide work for her six sons. The youngest, Tonino Benelli, emerged as an exceptional rider with a natural talent that combined with the company's engineering capabilities to produce early international success. In 1927 Benelli patented a cascade gear distribution system for overhead camshaft engines, an innovation that underpinned the company's racing machinery for decades and was immediately validated on the circuit: Tonino won the Italian Championship in 1927, 1928, and 1930 on a Benelli 175 SOHC, then in 1931 on a DOHC version. He also took second in the 1932 European Championship. His racing career was ended by a serious crash at the Tigullio circuit in 1932; he died from injuries sustained in a road accident in 1937.
Benelli continued without Tonino. The Belgian rider Yvan Goor won the European championship in the 175cc class in 1934 on a Benelli. In 1935, Raffaele Alberti set a world speed record for the kilometre and the mile in the 250cc category on a Benelli bialbero at 182.5 km/h. In 1939, English rider Ted Mellors won the Isle of Man TT Lightweight 250cc race on a Benelli, one of the most prestigious victories in pre-war motorcycle racing.
After the factory was partially destroyed during the Second World War and rebuilt, Benelli returned to competition immediately. In 1950, Italian rider Dario Ambrosini won the 250cc World Championship — the second year the FIM World Championship had been held — on a Benelli, giving the Pesaro manufacturer its first world title. Ambrosini also won the Italian national championship in the 250cc class that year.
Nineteen years later, Australian rider Kelvin Carruthers won the 250cc World Championship in 1969 on a Benelli, the manufacturer's second and final world title. Tarquinio Provini added national titles for Benelli in the 250cc Italian championship in 1965 and 1966, and Renzo Pasolini won the Italian 250cc and 350cc championships on Benelli machinery in 1968 and 1969.
The most celebrated episode in Benelli's Grand Prix history came in 1963. Tarquinio Provini, one of the most technically astute riders of the era, convinced Alfonso Morini to build a competitive 250 — then raced for Moto Morini — but Benelli's own 250 GP was also a front-running machine in this period. Benelli's greatest achievement in the 1963 season was demonstrated by Provini's extended battle with Jim Redman's multi-cylinder Honda. The season produced a tie on race wins, and the championship was not decided until the final round in Japan. The Honda factory refused to allow Provini to practise before the race, a deliberate competitive hindrance. Redman took the title over Provini by just two points.
In the context of the 1963 season, the Jarno Saarinen era also produced memorable results: Saarinen rode newly developed Benelli four-cylinder machines in 1972, winning in both the 350cc and 500cc classes at the Trofeo Pesaro Mobili event, beating Giacomo Agostini on MV Agusta and Pasolini. However, Italian-Argentine industrialist Alejandro de Tomaso — who had acquired Benelli in 1971 — withdrew all factory racing support following the death of Piers Courage in a De Tomaso Formula 1 car at Zandvoort, ending Benelli's Grand Prix chapter.
Under de Tomaso's ownership from 1971, and following a merger with Moto Guzzi that left Benelli diminished, the company's fortunes declined. A revival under Andrea Merloni from 1995 produced the Tornado Tre sports motorcycle, which competed briefly in the World Superbike Championship in 2001 and 2002, but the company again went into financial difficulty and was eventually acquired by China's Qianjiang Motor Group in 2005.
Benelli's Grand Prix legacy rests on two world championships, a pre-war Isle of Man TT victory, and a succession of Italian national titles spanning four decades. The Benelli and MotoBi museum in Pesaro, housed in a surviving building from the original factory at Viale Mameli 22, preserves approximately 200 motorcycles from the company's history, including racing machines from across the competitive eras.