ABSTRACT Live streaming technologies transform the information processing of customers by changing the way they interact with and acquire information. However, this emerging technological artefact may induce both positive and negative consequences for customer decision making. It is yet unknown what constitutes the dimensions of the juxtaposed IT affordances and how they affect customer behaviours in this new social phenomenon. This paper contributes to IS research by uncovering the specific bright and dark sides of IT affordances in live streaming e-commerce and by explaining the cognitive mechanisms underpinning customer purchase and brand citizenship behaviours. We employed a sequential mixed-methods design to embrace and contextualise the theory of affordance, vicarious learning, and cognitive load to rigorously develop a theoretical framework of the juxtaposed IT affordance in live streaming e-commerce. The results indicate that positive affordances (e.g., interactivity, visibility, and entertainment) have stronger effects on both economic and non-economic value. However, the potential dark side (e.g., broadcasting and source diversity) has more negative effects on purchase intention than brand citizenship behaviour, underscoring the importance of involving customers in co-creating brand-related value in live streaming e-commerce. Our findings contribute considerably to the emerging literature on live streaming e-commerce and provide actionable recommendations for practitioners.