<p>The present study investigates the impact of gamma radiation exposure on the linear and nonlinear optical properties of the CH₃NH₃PbBr₃ perovskite structure and the grown single crystal. The interaction between gamma radiation and CH₃NH₃PbBr₃ perovskite structure involves complex radiation-matter interactions that lead to both beneficial detection properties and detrimental degradation effects. Understanding these chemical reactions is crucial for optimizing perovskite-based radiation detectors while managing stability concerns. In this study, Samples are exposed to a ⁶⁰Co gamma source at various doses. Gamma radiation is a type of electromagnetic radiation with high energy, frequency, and penetrating power. Gamma radiations at precise doses can tune the nonlinear optical properties of CH₃NH₃PbBr₃ single crystals for various applications. The optical study was carried out using UV–Vis NIR spectroscopy in the reflectance mode. Photoluminescence spectra were obtained using a 410&#xa0;nm laser diode and a fiber spectrometer (model 4000) from Aurora. Furthermore, for the first time, the nonlinear optical parameters including the nonlinear refractive index, nonlinear absorption coefficient, and second-order hyperpolarizability constant, are calculated for both pristine and gamma-radiation exposed CH₃NH₃PbBr₃ single crystals with the Z-Scan technique. The Z-scan technique is used to measure the nonlinear optical properties of materials, and the curves provide information about the material’s response to light. The study of nonlinear optical (NLO) properties under different irradiations is crucial because it reveals how materials behave when exposed to irradiations. This behavior can be harnessed for various applications, including optical limiting, optical switching, and other photonic devices.</p>