Monoclinic ZnWO4 nanostructures with various concentration of Er were prepared by hydrothermal approach. The synthesized nanostructures were characterized by UV–vis spectra, X-ray diffraction (XRD) technique, steady-state and time-resolved fluorescence lifetime measurements. XRD results confirmed that Er3+ ions were successfully incorporated into ZnWO4 lattice without any secondary phase formation. The incorporation and energy transfer of Er into ZnWO4 were revealed by emission spectra and lifetime decay curves. The nonlinear optical properties of the nanostructures were studied by continuous wave Z-scan technique at 532 nm using Nd: YAG laser. From the open aperture and closed aperture Z-scan traces, the extracted nonlinear absorption and refraction data are attributed to reverse saturable absorption and self-defocusing nature of the samples. The optical nonlinearity of the nanostructures was found to be increasing with increased Er3+ dopant concentration. The observed nonlinearity suggests that the synthesized nanostructures could be explored for its applications in advanced photonic devices. © 2019 Elsevier B.V.