Chalcogenide perovskites are emerging as a promising alternative to hybrid halide perovskites for optoelectronic applications, owing to their excellent light absorption and chemical stability. This study investigates the performance of single‐ and dual‐absorber solar cell devices using InBiSe3 and GaBiSe3 as absorber materials, simulated using the solar cell capacitance simulator in one dimension software. The devices employ WS2 as the electron transport layer and CuO as the hole transport layer. For single‐absorber devices, GaBiSe3 achieve a power conversion efficiency (PCE) of 26.58%, with a VOC of 0.94 V, a fill factor (FF) of 86.82%, and a short‐circuit current density (JSC) of 32.52 mA cm−2. InBiSe3 performs slightly lower, with a PCE of 21.44%, VOC of 1.25 V, FF of 87.83%, and JSC of 19.49 mA cm−2. The bilayer configuration, incorporating InBiSe3 as the top layer and GaBiSe3 as the bottom layer, shows the highest efficiency of 30%, with a VOC of 1.06 V, JSC of 32.78 mA cm−2, and FF of 85.97%. The study also examines the effects of temperature, shunt resistance, and series resistance on the device performance, as well as the influence of absorber layer thickness, defect density, and back contact variations.