Recently, transition metal dichalcogenide (TMDC) materials have attracted considerable attention due to their excellent nonlinear optical (NLO) properties. Their unique characteristics, including ultra-broadband absorption, strong nonlinear optical responses, and potential applications in optical limiting, saturable absorption, pulsed laser generation, and biosensing, have been extensively studied. In this work, we report, for the first time, an investigation of the nonlinear optical properties of FTO/MoS₂–MoO₂–MoO₃ composite thin films deposited on fluorine-doped tin oxide (FTO) substrates by electrodeposition. Strong light–matter interactions under high-intensity laser irradiation can induce nonlinear optical responses in such materials. Therefore, the nonlinear absorption and nonlinear refraction characteristics of the prepared films were examined using the Z-scan technique under continuous-wave laser excitation at 532 nm with an output power of 180 mW. The obtained results reveal pronounced saturable absorption behavior. The observations indicate that nonlinear absorption and nonlinear refraction are negligible at low laser powers; however, at higher laser intensities, significant nonlinear optical effects emerge. Furthermore, modifications in the chemical composition of the material, specifically a decrease in sulfur content accompanied by an increase in oxygen content, lead to enhanced nonlinear absorption and reduced nonlinear refraction. These findings demonstrate the strong dependence of the nonlinear optical response on both the excitation intensity and the chemical structure of the MoS₂–MoO₂–MoO₃ composite films.