Abstract Pure and Ni-doped ZnO nanoparticles were synthesized using a simple co-precipitation method for malachite green (MG) dye removal. Structural and compositional analyses (scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy) confirmed the successful incorporation of Ni2+ into the ZnO lattice, resulting in a morphological transition from spherical to mixed spherical/rod-like forms and a reduction in crystallite size