Purpose: The purpose of this study is to investigate how sports fans' loyalty is built via CSR activities of professional sports teams. Furthermore, the study sought to suggest the model presenting the process of developing loyalty of sport fans by teams' CSR performance. Research design, data, and methodology: For this purpose, a survey was conducted on 450 professional sports fans through the convenience sampling method. A total of 357 of the data were used for the final analysis. Based on the collected data, frequency analysis, reliability analysis, confirmatory factor analysis, and structural equation model analysis were conducted. Results: The results showed that CSR activities contribute to building a positive image of team. Regarding fan identification, team image has also a positive effect on enhancing identification. The finding has supported the notion that attitudinal loyalty is enhanced by fan identification and further attitudinal loyalty significantly influences behavioural loyalty of fans. Conclusions: The results of this study explored the function of CSR of the teams on attitudinal and behavioural outcomes, loyalty. Moreover, the study suggested the constructual model presenting its role on enhancing fans' attitudes and behaviour affecting participation and consumption. Academic and practical implications were discussed for sport marketers and practitioners.