In this paper, brush-like ZnO nanowires were synthesized by two-step method combining electrospinning and hydrothermal. The phase purity, morphology, and structure of the brush-like ZnO hierarchical structures were characterized, which exhibited the improved surface area, comparing with ZnO nanofibers. The gas-sensing experiments were carried out on brush-like ZnO nanowires and ZnO nanofibers sensors under optimum working temperature. The highest response of brush-like ZnO nanowires to 100 ppm toluene and CO can reach to 12.7 and 5.9, respectively, which was much higher than that of ZnO nanofibers. Moreover, the brush-like ZnO nanowires sensor also shows fast response/recovery time to toluene (9/4 s) and CO (6/2 s), low detection limit (1 ppm to toluene). The measured results demonstrate that brush-like ZnO nanowires are potential as a novel sensing material for practical gas-sensing applications.