A novel bismuth halide oxide nanomaterial, bismuth oxychloride nanoplates (BiOCl NPs), was firstly applied in organic solar cells (OSCs) as a hole transporting layer (HTL) to substitute the widely-used PEDOT:PSS. It is worth noting that the BiOCl NPs can be synthesized at ~1/200 cost of the commercial PEDOT:PSS under facile conditions and can be well dissolved in green solvents. Different from PEDOT:PSS interlayer, the deposition of BiOCl HTL is free of post-treatment at elevated temperature, reducing device fabrication complexity and minimizing energy consumption. To verify the universality of BiOCl in improving photovoltaic performance, OSCs containing three representative active layers were investigated. Encouragingly, power conversion efficiencies (PCEs) of the well-studied P3HT:PC61BM, PTB7-Th:PC71BM, and PM6:Y6-based OSCs with the novel BiOCl HTL were boosted from 3.62%, 8.78%, and 15.63% to 4.24%, 9.92%, and 16.11%, respectively, compared to the PEDOT:PSS based devices. The structure-property correlation is also established via a series of material and device characterization techniques, demonstrating that the superior performances of the BiOCl-based OSCs are benefited from the sufficient oxygen vacancies and more effective interfacial contact. Moreover, the BiOCl-based OSCs can maintain 80% of the original PCEs after 360 h, showing a much better stability than the cells with the PEDOT:PSS interface (~50% degradation).