At age 22, Adalberto Garelli received a degree in engineering and dedicated his work to developing and perfecting the two-stroke engine for Fiat. Garelli quit in 1911 due to Fiat's lack of enthusiasm for the two-stroke engine. He continued his own engine design between 1911 and 1914 which resulted in the 350 cc split-single cylinder engine. Garelli worked for other motorcycle manufacturers from 1914 to 1918 during which time he won a competition organized by the Royal Italian Army to design a motorcycle with which he used his 350 cc split-single engine.

Garelli Cross 1968.
Garelli City Bike 1972.

In 1919, Garelli constructed a 350 cc motorcycle which set a long-distance record from Milan to Naples. Rider Ettore Girardi covered the 840 km (520 mi) with an average of 38.29 km/h (24 mph). Many famous Italian racers such as Ernesto Gnesa, Tazio Nuvolari and Achille Varzi began their racing careers on Garelli bikes. The Garelli 350 cc split-single stayed in production until 1926 and made a major impact in racing. The company also produced motorcycles for the Royal Italian Army. After World War II, Garelli concentrated on producing smaller bikes and mopeds for the European market.

1980 Garelli Grand Sport LTD Moped

In the 1970s Garelli produced the Tiger Cross MK 1 which was an off-road 2 stroke enduro motorcycle. The Tiger Cross was produced in 1976. The motorcycle was painted black and yellow.

In 2019, in the centenary year of the foundation, the brand returned into the market with fully electric products: Ciclone Sic58 and E-Bike Ciclone Sic58. In collaboration with the Marco Simoncelli Foundation.