The utility of carbonaceous materials for hybrid semiconductor photocatalysts has been rapidly increasing in recent years due to the synergetic effect via interfacial charge transfer reactions. In this study, we prepared a novel graphdiyne–ZnO nanohybrid by the hydrothermal method and examined its photocatalytic properties on the degradation of two azo dyes (methylene blue and rhodamine B). Interestingly, the graphdiyne–ZnO nanohybrids showed superior photocatalytic properties than that of the bare ZnO nanoparticles as evidenced by the absorption spectra and total organic carbon analyses. Moreover, the rate constant of graphdiyne–ZnO nanohybrids is nearly 2-fold higher compared to that of the bare ZnO nanoparticles on the photodegradation of both azo dyes. Further, a plausible mechanism for the enhanced photocatalytic properties of the graphdiyne–ZnO nanohybrids has been discussed. This work on the development of graphdiyne-based semiconductor photocatalysis can provide new insights into the design of novel hybrid photocatalysts for potential applications in the environmental remediation sectors.