Solar cells exhibit high performance using a thin semiconducting film with superior light-harvesting ability. Though a variety of thin-film solar cells have shown promise, the quest to find cheaper and promising alternatives is necessary. Herein, this study provides evidence of the capabilities of cheap and stable copper bismuth oxide or CuBi2O4 (CBO) as an efficient light absorber for thin-film photovoltaics. Solar Cell Capacitance Simulator-1D (SCAPS-1D) software is used to optimize the performance of CBO-based kusachiite solar cells with various n-type metal sulfide (MS) buffer layers (CdS, WS2, SnS2, and ZnS). The variation in the thickness and acceptor and donor doping density of CBO light absorber and MSs buffer layers film had the highest control over power conversion efficiency (PCE) and other solar cell parameters. The effect of the work function of metal back contact and operating temperature on the performance of solar cells is also analyzed to assess the real-time application of the proposed metal sulfide and CBO-based kusachiite solar cells. The solar cell device structure of ITO/WS2/CBO/Au optimized in terms of thickness and doping density has shown a theoretical PCE of 22.84 %.