This manuscript describes the accurate deposition of carbon on the surface of ZnO nanorods by a simple, microwave-assisted method and the studies on the cytotoxicity and photocatalytic activity of the C/ZnO hybrids. For the coating of carbon, the surface of the preformed ZnO nanorods were first modified by amino groups and then grafted by glucose, and finally they were irradiated in a microwave field to induce the transformation of glucose into carbon. With this method, the as-prepared carbon-coated product preserved the good dispersity and uniformity of the initial ZnO nanorods. Studies on the effects of carbon-coated ZnO nanorods and pure ZnO nanorods on cultured mouse fibroblast cells revealed that the coating of biocompatible carbon remarkably reduced the cytotoxicity of ZnO nanorods. In addition, benefiting from the synergy effect of carbon and ZnO, carbon-coated ZnO NRs also exhibited excellent photocatalytic activity toward the decomposition of methylene blue in a short time (approximately 14 min).