The circular supply chain (CSC) plays a pivotal role in delivering sustainable products to end users, profoundly affecting organizational performance and societal welfare. In this ecosystem, effective Product Return Management (PRM) is crucial, as consumers play a pivotal role in returning used products for reuse or recycling. Despite its significance in waste reduction and attaining environmental and economic goals, scant research has explored product return barriers within CSC. This study bridges this gap by investigating and prioritising these barriers to enhance the circular economy. Employing a systematic literature review (SLR), we extracted and screened 13 product return barriers in CSC using the Grey Delphi method. Subsequently, we introduced an enhanced version of the Group Grey-Best-Worst Method (GG-BWM), a novel approach that harmonises expert judgments by addressing uncertainties through Grey Theory and incorporating both individual-level and group-level inconsistency ratios. The findings highlight lack of motivation, lack of consumer awareness, and lack of proper infrastructure as the most critical barriers. Furthermore, sensitivity analysis conducted across 11 scenarios emphasises the significance of our results. This study contributes to the group multiple criteria decision making (MCDM) methods and CSC literature, while offering actionable insights practitioners seeking to improve the effectiveness of their CSC strategies.