This study explores the role of sustainability practices in facilitating the adoption of a circular business model within the readymade garment (RMG) sector in Bangladesh. Specifically, the study wants to investigate how green supply chain practices (GSCPs), green investment (GI), and green human capital (GHC) contribute to ensuring sustainability practices in RMG (SRMG) and transitioning businesses towards a circular economy (CE). A survey of 589 Bangladeshi RMG managers using a 7-point Likert scale informed this quantitative study. PLS-SEM revealed significant predictor–outcome correlations, while necessity condition analysis (NCA) identified essential conditions for desired outcomes. This study found that GSCM, GHC, and SRMG practices significantly and positively influence CE adoption. Additionally, it revealed that sustainable practices (SPs) mediate the relationship between GSCM, GSC, GI, and CE adoption. This study enriches existing knowledge by exploring key relationships in the proposed model, highlighting significant direct and indirect effects.