Social media enables the public to learn first aid knowledge conveniently. However, factors facilitating individuals to adopt first aid knowledge on social media are unclear. The information adoption model (IAM) has been widely used as a theory to explain individuals’ information/knowledge adoption behavior. Prior studies based on IAM focused on the effect of cognition but neglected the impact of emotion. This study aims to investigate both effects of cognition (e.g., perceived information usefulness) and emotion (e.g., arousal) on first aid knowledge adoption and examine their corresponding antecedents. The hypothesized model was validated with a structural equation modeling approach using data collected from 375 social media users in China. In addition to identifying the antecedents of arousal, the results confirmed the critical role of arousal and its interaction effect with perceived information usefulness in facilitating first aid knowledge adoption. This study can extend IAM and health literature and suggest practitioners consider emotion during health governance and first aid knowledge popularization.