An engine-and-electric-machine assembly, including an engine (8) and an electric machine (9). The crankshaft (7) of the engine (8) has an extension section (7-3) that extends to the exterior of the engine (8), and the rotor (3) of the electric machine (9) is mounted to the extension section (7-3). The present disclosure improves the integration level of the engine-and-electric-machine assembly, and reduces the weight and volume of the engine-and-electric-machine assembly. A vehicle driving device including the engine-and-electric-machine assembly is also disclosed.