This study investigates the influence of affiliate marketing, live streaming, and price discount on the purchase decisions of fashion products among TikTok users in South Jakarta, an emerging hub of social commerce. The problem addressed is the effectiveness of these digital marketing strategies, which, despite the rapid growth of e-commerce, remains inconsistent across previous findings and requires further re-examination. Data were collected from 120 valid respondents using an online questionnaire distributed through purposive sampling, focusing on TikTok Shop fashion buyers in South Jakarta. The survey sought to understand how these three variables, acting as external stimuli within the Stimulus–Organism–Response (SOR) framework, influence consumers’ purchase decisions. Partial Least Squares Structural Equation Modeling (PLS-SEM) with SmartPLS 4 was employed for analysis. Findings indicate that affiliate marketing, live streaming, and price discount each have a positive and significant effect on purchase decisions, with price discount showing the strongest effect while affiliate marketing and live streaming show comparable effects. This highlights that the model explains 67.4% of the variance in purchase decision, confirming the applicability of SOR theory in social commerce. The results provide insights into effective digital marketing strategies and offer practical implications for fashion businesses to optimize affiliate content, live streaming, and price discount strategies to drive purchase decisions on TikTok Shop.