Blue–violet lasing action in a single ZnO microbelt has been demonstrated at room temperature. The microbelts, with widths of about 0.65μm and lengths up to several millimeters, have been synthesized via the vapor-phase transport method with CuO catalyst at 900°C. Under a direct-current voltage excitation, surface-emitting lasing actions from the microbelts treated by hydrogen plasma were observed in hydrogen gas ambient. The luminescence spectrum exhibits a series of sharp peaks with a maximum at 481.2nm and the full-width at half-maximun of 0.3nm. The results strongly suggest that hydrogen is one of the primary origins of blue–violet laser. The facilitation of fabrication and the low dimensionality of these microbelts make them ideal miniaturized laser light sources for optoelectronic applications.