This study aims to analyze the influence of Social Media Marketing, Brand Trust, and Social Media Engagement on purchasing decisions for Wedding Organizer services at Naza Collection. The background of this research stems from the increasingly competitive wedding service industry in the digital era, where consumers heavily rely on online information before making purchasing decisions. The research method used is quantitative with a survey technique through distributing questionnaires to 102 respondents who are consumers or potential consumers who have interacted with Naza Collection's social media. Data analysis was conducted using Partial Least Squares Structural Equation Modeling (PLS-SEM) with SmartPLS 4. The results showed that: (1) Social Media Marketing has a positive and significant effect on purchasing decisions with a path coefficient of 0.252 (P-value < 0.001, f² = 0.094); (2) Brand Trust has a positive and significant effect with a path coefficient of 0.441 (P-value < 0.001, f² = 0.288) and is the most dominant factor; (3) Social Media Engagement has a positive and significant effect with a path coefficient of 0.206 (P-value 0.021, f² = 0.064); (4) simultaneously, the three variables have a significant effect with an R-square of 0.345 (moderate category). These findings confirm that Brand Trust is the key driver in encouraging purchasing decisions for Wedding Organizer services, thus companies are advised to focus on building brand trust through consistency in service quality and information transparency on social media.