ZnO nanomaterials with different morphologies such as nanoflakes, spherical nanoparticles (SNPs), and nanorods have been synthesized via a simple low temperature coprecipitation method. The concentration of the capping agent is a key factor in the morphological control of ZnO nanostructures. Triton X-100 micelles were found to be single molecules at low concentration but spherical and rod-like shaped micellar aggregation at higher concentrations. The formation of different morphologies of ZnO was confirmed by HR-SEM and HR-TEM. XRD data showed the formation of single-phase ZnO with the wurtzite crystal structure. The influence of Zr contents on the structure, morphology, absorption, emission, and photocatalytic activity of ZnO SNPs was investigated systematically. The influence of the ZnO morphologies on the photocatalytic degradation (PCD) of resorcinol as a model reaction is evaluated and discussed in terms of particle size, surface area, crystal growth habits, and oxygen defects. The results indicated that the particle size is an important factor for the PCD, and thus, the 1.5 wt % Zr-doped ZnO SNPs show superior performance toward PCD of resorcinol than other samples due to the small particle size distribution. Furthermore, the effect of different photocatalytic reaction parameters on the resulting PCD efficiency of ZnO SNPs was investigated.