This study seeks to explore the correlation between the variables of social media marketing, brand loyalty, self-congruence, brand trust, and brand image, both directly and indirectly. The examination focuses on global fast fashion brands, namely Zara, H&M, and Uniqlo. The research employs a quantitative approach, gathering data through Google Forms electronic questionnaires. Conducted in Indonesia, the study targets respondents in major cities (Jabodetabek). Data analysis involves both outer and inner models using Smart-PLS 4.0. The outer model includes validity and reliability tests, while the inner model assesses goodness of fit, Common Method Bias, R-square, Predictive Relevance, T-statistics, and P-value. Moreover, structural equation modelling is conducted to assess construct relationships within the study's theoretical framework. The findings indicate that social media marketing affect all variables, and that all variables affect brand loyalty positively and significantly. In conclusion, this study not only contributes to the international marketing and brand management strategies of fast fashion in emerging markets, but also enhances fast fashion's appeal by fostering brand loyalty through social media marketing.