Preparation of coaxial (core–shell) CdS–ZnS and Cd1–xZnxS–ZnS nanowires has been achieved via a one-step metal–organic chemical vapor deposition (MOCVD) process with co-fed single-source precursors of CdS and ZnS. Single-source precursors of CdS and ZnS of sufficient reactivity difference were prepared and paired up to form coaxial nanostructures in a one-step process. The sequential growth of ZnS on CdS nanowires was also conducted to demonstrate the necessity and advantages of the precursor co-feeding practice for the formation of well-defined coaxial nanostructures. The coaxial nanostructure was characterized and confirmed by high-resolution transmission electron microscopy and corresponding energy dispersive X-ray spectrometry analyses. The photoluminescence efficiencies of the resulting coaxial CdS–ZnS and Cd1–xZnxS–ZnS nanowires were significantly enhanced compared to those of the plain CdS and plain Cd1–xZnxS nanowires, respectively, owing to the effective passivation of the surface electronic states of the core materials by the ZnS shell.