["Journal of Consumer Behaviour, EarlyView. ", "\nABSTRACT\nConsumers increasingly use social media posts to actively manage the randomness of blind boxes in purchasing, turning what was once a complete mystery into a calculated risk. As user‐generated content reveals extraction strategies and probability cues, the mystery traditionally associated with blind box purchases gives way to managed uncertainty. This study examines how consumers sustain motivation to purchase co‐branded blind boxes when outcome uncertainty is reduced but not eliminated. Using a netnographic analysis of 181 Rednote posts and 22 semi‐structured interviews, the findings identify a triadic motivational system comprising co‐brand‐related, product‐related, and social‐related drivers. Co‐brand motivations involve nostalgic self‐continuity and identity reinforcement; product motivations reflect anthropomorphic attachment and enjoyment of the unboxing process; and social motivations derive from status, recognition, and belonging within online communities. This study conceptualises co‐branded blind box consumption as post‐uncertainty hedonic behaviour in which consumers transform probabilistic purchases into cognitively engaging and socially embedded practices. This study primarily contributes to uncertainty literature by conceptualising co‐branded blind box consumption as post‐uncertainty hedonic behaviour. It also clarifies how social media serves as a field of meaning production that reconfigures the role of uncertainty in contemporary consumption.\n"]