This study aims to identify the factors influencing the intention to select sustainable fashion products among Generation Z in Vietnam, while clarifying the role of social media communication in the factors shaping this intention. The research model is constructed based on an extended Theory of Planned Behavior (TPB), incorporating additional variables: Social Media (SM) and Cultural-Environmental Concern (CE). A quantitative research method was employed through an online survey, yielding a sample of 205 Generation Z consumers (aged 15 to 25). Data were analyzed using SMARTPLS 4 software to evaluate the measurement model and test the PLS SEM. The findings indicate that social media communication exerts a significant positive impact on all four mediating factors: Attitude (AT), Subjective Norms (SN), Perceived Behavioral Control (PBC), and Cultural-Environmental Concern (CE). Among these, three factors were found to directly and statistically significantly stimulate Selection Intention (PI), specifically: Perceived Behavioral Control (path coefficient of 0.334), Subjective Norms (0.243), and Attitude (0.240). Conversely. Cultural-Environmental Concern (CE) did not demonstrate sufficient statistical significance to establish a relationship with the intention to select sustainable fashion products. Based on these results, the paper proposes managerial implications for fashion enterprises to optimize social media content strategies and enhance product accessibility to promote sustainable consumption.