The rapid growth of e-commerce and the increasing number of online shoppers have brought the topic of online shopping to the forefront of public and scholarly discourse. A distinguishing characteristic of online shopping, in contrast to traditional purchasing processes, is the temporal displacement between the decision to purchase and the actual receipt of the product, which has resulted in a surge of product returns. Consequently, the leniency of return policies has emerged as a critical determinant of consumer behavior. However, existing research has paid limited attention to the influence of online shopping return policy leniency on consumer purchase intention from multiple internal perceptual perspectives. To address this research gap, this study employs signal theory and utilizes the SOR (Stimulus-Organism-Response) analytical framework to develop a model that considers the perceived quality and perceived risk as mediating variables, while store reputation and product heterogeneity serve as moderating variables. This comprehensive model aims to investigate the impact of return policy leniency on consumer purchase intention. This study employs a multifactor experimental design, in which eight different experimental groups are created in online shopping contexts by manipulating the leniency of the return policy，product heterogeneity, and store reputation: 2 (return policy: lenient, strict) × 2 (product heterogeneity: high, low) × 2 (store reputation: high, low). The study examines the direct effect of return policy leniency on consumers’ perceived quality and risk, the mediating role of these perceptual factors on purchase intention, as well as the moderating influence of product heterogeneity and store reputation. Empirical findings indicate that: (1) lenient return policies engender higher perceptions of quality and lower perceptions of risk, thereby augmenting consumer purchase intention; (2) in high-reputation stores, the impact of return policy leniency on consumer-perceived quality and risk is more pronounced compared with low-reputation stores; (3) when consumers encounter products with weaker heterogeneity as opposed to stronger heterogeneity, return policy leniency exerts a more substantial influence on perceived risk, while its impact on perceived quality remains statistically insignificant. The potential contributions of this study are manifold: (1) the investigation delves into the impact of online retailers’ return policy leniency on consumer perceived quality and risk from various internal perceptual perspectives, thereby integrating relevant arguments from signal theory; (2) by employing the stimulus-organism-response model, the study elucidates the underlying mechanisms through which return policy leniency influences consumer purchase intention within the context of online shopping, with perceived quality and perceived risk serving as mediating variables; (3) the study adopts a dual perspective, considering both the product and store dimensions, and unveils the moderating role of product heterogeneity and store reputation in the relationship between return policy leniency and consumer perceived quality and risk within the realm of online shopping. Consequently, this study holds theoretical implications for advancing and refining the SOR model, signal theory, and research on the leniency of return policies in online shopping. Furthermore, it offers practical insights for consumers, online retailers, and e-commerce platforms.