Photovoltaic materials such as chalcogenide perovskites have gained interest due to their stability, non-toxicity, and lead-free nature. However, the band gap of CaZrSe3 (1.3–1.5 eV) is closer to the ideal 1.4 eV required for maximum theoretical efficiency. In the present study, we investigate the effect of pressure on the electronic, optical, and photovoltaic properties of distorted chalcogenide perovskite (GdFeO3 structure type) CaZrSe3. The results show that increasing pressure from 0 to 10 GPa reduces the energy band gap without altering its direct nature at the Г-point. CaZrSe3 exhibits significant optical responses in the visible and ultraviolet energy ranges, making it a promising and environmentally friendly perovskite suitable for photovoltaic applications. Additionally, the optimized SCAPS-1D result suggests that at pressures of 2 GPa and 6 GPa, the proposed model achieves the highest power conversion efficiency compared to all other pressure conditions.