The apparel industry's sustainability is gaining scholars' attention amidst increasing concerns about its environmental impacts. However, to ensure that the industry's efforts in environmental preservation succeed, it is crucial to identify the factors that can positively influence consumers' purchase or buying intentions for green apparel. However, at present, this topic is relatively understudied. Assimilating the norm activation model (NAM) and the stimulus–organism–response (SOR), we investigate economic, cognitive and ecological factors as antecedents to consumers' green apparel buying intentions. Additionally, we adapt the model to consider consumers' knowledge about apparel production as a moderator. Empirically analysing data from 478 apparel consumers from the USA through structural equation modelling, we found significant roles for affordance, ecological concerns and ascription of responsibility as stimuli influencing an individual's cognitive state through green self‐efficacy, green attitude and personal norms. The latter, in turn, affects the individual's buying intentions. Our findings entail several suggestions to help scholars, policymakers and business managers positively influence consumers to make green purchase decisions. We contribute significantly to the literature by explaining the nuances of driving factors that promote green apparel buying, and practitioners can leverage them to devise appropriate strategic tactics supporting such consumption practices.