This study investigates the influence of user-generated content (UGC) on consumer engagement within TikTok, one of the fastest-growing social media platforms. While brand-generated campaigns remain a dominant marketing strategy, UGC has emerged as a credible and authentic alternative that shapes online purchasing decisions. The research examines key factors affecting audience interaction, including content authenticity, credibility, perceived value, satisfaction, and content type, with a comparative perspective on UGC and brand-generated content. An empirical survey of 1,090 TikTok users, primarily women aged 18–24, was conducted, and the data were analyzed using Partial Least Squares Structural Equation Modeling (PLS-SEM). Eight hypotheses were tested, addressing the relationships between authenticity, credibility, value, satisfaction, and engagement. Results indicate that seven out of eight hypotheses were supported, highlighting authenticity and perceived value as central drivers of audience interaction. While source credibility strongly influenced content credibility, it did not directly affect audience engagement, suggesting that on TikTok, the content itself outweighs the creator’s status. The findings provide theoretical insights into consumer behavior on short-form video platforms and practical implications for marketers. Brands that leverage UGC strategies can foster authenticity, strengthen trust, and increase user engagement, ultimately improving loyalty and purchase intentions.