Abstract: Objective: This study aims to explore accounting methods and analytical steps for quantifying the carbon footprint of mass participants in sports events, which represents a significant yet challenging component of event-related emissions. Methods: A questionnaire was designed using the carbon emission coefficient method, covering three dimensions: demographic information, sports participation history, and emission behaviors during events. The study surveyed mass participants across four major types of sports events in China: comprehensive sports events, tournament-based sports events, mass sports events, and professional sports events. Based on this data, carbon footprint results and comparative distribution analyses were conducted. Results: Intercity transportation accounted for the largest proportion of carbon footprints among mass participants, with tournament-based sports event spectators exhibiting higher per capita carbon footprints compared to other event types. The carbon footprint of mass participants was influenced by the event’s public activity characteristics and sport-specific features. Key determinants included the host city’s green public transportation infrastructure, geographic location and accessibility of the venue, event scheduling and format, as well as participants’ demographic profiles and consumption habits. Conclusions: Establishing a scientifically robust carbon footprint measurement framework for mass participants particularly for the sports events in this country is both necessary and urgent. Future research should focus on longitudinal tracking studies to refine the carbon footprint assessment system.