This manuscript explores the effects of iron doping on the structural, optical, and photocatalytic properties of ZrO2 nanoparticles (NPs) for photocatalytic applications. Techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and UV–visible spectroscopy were used to investigate the characteristics of synthesized materials. The XRD pattern of ZrO2 indicates a pure monoclinic phase structure and strong diffraction orientation along the (1¯11) direction; with adding Fe with different concentrations, a new phase appeared, indicating ZrO2 NPs with tetragonal phase structure with strong diffraction orientation along the (101) direction as well as Fe concentrations increase, new phases appeared, namely α-Fe2O3, Zr3Fe, and Zr4Fe2O0.6. The observed trend in the crystallite size decreases from 25 nm to 13 nm with increasing Fe concentrations. The NPs’ optical bandgap was found to be 4.28 eV, reducing to 2.93 eV as the concentration of Fe increased. This value is in good agreement with those previously published for photocatalytic applications. The photocatalytic performance was determined and found to obey a first-order rate constant where the best-performing sample was FZO-10 with methylene blue degradation (94 %) and k values (36.2 × 10 −3 min −1), respectively. Additionally, the mass attenuation coefficient and half-value layer analysis revealed significant attenuation properties, showing a consistent decrease in GMAC with increasing gamma energy and highlighting the impact of ZrO2 concentration on gamma-ray shielding effectiveness. The outcomes demonstrate that Fe doping has a significant effect and has the potential to improve ZrO2-based photocatalytic applications’ performance.