This study examines the influencers that significantly impact the purchasing behavior of Generation Z (Gen Z) customers in the e-commerce and cosmetics industries in Vietnam. By employing a mixed-methods approach, data was collected from 600 Gen Z customers in Vietnam, and behavioral intention models were used to understand their behavior. Specifically, 5 key characteristics of influencers such as trustworthiness, attractiveness, expertise, influencer match-up congruence with the brand/ product, and negative publicity are hypothesized to have significant impact on behavioral intention of Gen Z customers. The results of this research indicate that influencers play a significant role in shaping Gen Z customers' purchasing behavior in the e-commerce and cosmetics industries. Trustworthiness, attractiveness, and expertise were found to be crucial factors influencing Gen Z's decision-making process. Interestingly, the study reveals that influencers have a stronger impact than previously assumed, surpassing the theoretical expectations. The implications of these findings are significant for marketers and brands in developing effective influencer marketing strategies targeted at Gen Z customers in Vietnam. It is recommended that brands prioritize collaborating with trustworthy and compatible influencers who can create a positive brand image. Future research should consider additional factors and conduct cross-cultural comparisons to further enhance our understanding of Gen Z's behavior and the role of influencers.