The Lyon trolleybus system is part of the public transport network of the city and commune of Lyon, France. Opened in 1935, it combines with the Lyon Metro, the Lyon tramway network and Lyon's urban motorbus network to form an integrated system.

A trolleybus is an electric bus that draws power from dual overhead wires using spring-loaded trolley poles. Two wires, and two trolley poles, are required to complete the electrical circuit. This differs from a tram or streetcar, which normally uses the track as the return path, needing only one wire and one pole. They are also distinct from other kinds of electric buses, which usually rely on batteries. Power is most commonly supplied as 600-volt direct current, but there are exceptions.