Abstract: As a global media event, the Olympic Games significantly influence public sports cognition and participation practices. Grounded in the knowledge gap theory and the "knowledge-attitude-practice" (KAP) model of health communication, this study constructs a "media exposure-knowledge-behavior" analytical framework to investigate the mechanism through which Olympic media exposure affects individuals' willingness to participate in sports. Based on an empirical analysis of 1,035 valid survey responses, the study finds: (1) Disparities in socioeconomic status significantly shape the Olympic knowledge gap, with individuals of higher education and income levels demonstrating superior objective knowledge; (2) New media platforms, through algorithmic recommendations and visual storytelling, significantly enhance users' objective Olympic knowledge, whereas traditional media show limited knowledge effectiveness due to a lack of interactivity; (3) The influence of Olympic media exposure on sports participation willingness varies by media type—traditional media stimulate embodied exercise motivation through in-depth narratives, while entertainment-oriented platforms like Douyin weaken users' motivation for physical activity; (4) Olympic knowledge serves as a key mediating variable between media exposure and participation willingness. This study systematically demonstrates the pivotal role of Olympic knowledge in the media effects chain and reveals the differential effects of various media. It not only deepens the theoretical understanding of the "media-to-behavior" transformation mechanism but also provides empirical evidence for designing public health communication strategies that leverage major media events to effectively enhance public participation in fitness.