Social Media Marketing, Trust, Reputation, and Loyalty among Indonesian Global Fast Fashion Consumers

This study examines the influence of social media marketing (SMM) on brand loyalty among Indonesian Generation Z consumers of global fast fashion brands, specifically Zara, H&M, and Uniqlo, with brand advocacy, brand trust, and brand reputation as mediating variables. Using a quantitative explanatory approach, data were collected from over 200 active social media users and analyzed using Partial Least Squares–Structural Equation Modeling (PLS-SEM) via SmartPLS 4. The results reveal that SMM significantly influences brand advocacy (β = 0.142, p = 0.021), brand reputation (β = 0.138, p = 0.029), and brand loyalty (β = 0.116, p = 0.045), while no significant direct effect on brand trust was found (β = 0.059, p = 0.364). Brand advocacy emerged as the strongest predictor of both brand trust (β = 0.673, p < 0.001) and brand loyalty (β = 0.490, p < 0.001). Brand reputation also significantly predicted loyalty (β = 0.267, p = 0.002) and partially mediated the advocacy–loyalty relationship. Contrary to conventional findings, brand trust did not significantly predict brand loyalty (β = 0.031, p = 0.714), suggesting a contextual boundary condition in the trust loyalty relationship within the fast fashion industry. The novelty of this study lies in its integration of brand advocacy, trust, and reputation into a unified multi-mediation model within the Indonesian fast fashion context a combination rarely examined simultaneously in the existing literature. This study contributes to the development of digital brand loyalty theory and offers practical implications for marketers to design advocacy-driven social media strategies that build sustainable consumer relationships in emerging digital markets.