Background: Sport can impact the protection of the environment and energy. Sports activities could gather people in one place, which may negatively affect the environment, such as noise pollution, antisocial behaviors, waste, air pollution, and sharp lighting. Objectives: This paper aims to investigate the role of sport in sustainable environmental development. This applied-developmental study utilized an exploratory qualitative method to collect data. Methods: The statistical population included all top managers of sports organizations (including the National Olympic Committee, Ministry of Sports, and all sports federations), specialists and experts in sport management in Iran, and some managers of the Iranian Department of Environment. Thirteen experts were selected using the purposive sampling method and snowballing technique. The semi-structured interview was used as a data collection tool. Data analysis was done with grounded theory through open, axial, and selective coding. Results: The results indicated that the pattern of sustainable environmental development based on the sport consists of 211 concepts and 26 subcategories. Categories 4, 4, 5, 8, and 4 were related to the causal factors, the fields, and domains, mediating variables, strategies, and consequences, respectively, and one category was also considered an axial phenomenon. Adequacy measure of the research process and quality of data and interpretations was approved based on credibility, transferability, dependability, confirmability, honesty, and data-derived theory criteria, including conformity, comprehensiveness, generality, and controllability. Conclusions: According to the results from the model, the sustainable environmental development based on the sport is affected by foresight, environmental values of sport, environmental requirements of the sport, green sports movement, educational and research factors, communication and promotional elements, economics, structural factors, and organizational factors, which can lead to green productivity in sports and the quality of life and well-being of citizens. [ABSTRACT FROM AUTHOR]