We present the structural and third order nonlinear optical properties of Sr2+-doped ZnO nanostructures synthesized by chemical precipitation technique. The prepared nanoparticles are systematically investigated by UV–vis absorption, X-ray diffraction (XRD), Photoluminescence spectroscopy and Field emission scanning electronic microscopy (FESEM), respectively. UV–vis absorption spectra show that the particles have a higher absorption in UV region and possess a large optical transparency in visible region. XRD patterns show that all the prepared nanoparticles are well crystallized with hexagonal wurtzite structure. The incorporation of Sr in ZnO was also confirmed by fluorescence quenching. FESEM images showed the formation of nanostructures with sheet-like structure. Third-order nonlinear optical properties of the nanostructures have been studied by Z-scan technique using diode pumped continuous wave (cw) laser system at a wavelength of 532 nm. Experimental results reveal that the materials exhibit saturable absorption (SA) and self-defocusing nature. © 2018 Elsevier Ltd