The rapid growth of social media has significantly transformed the landscape of marketing, with influencer marketing emerging as a dominant strategy to reach younger audiences—particularly Generation Z. This study investigates the impact of influencer marketing on Gen Z’s purchase decisions, examining how different social media platforms—such as Instagram, YouTube, and TikTok—shape consumer behavior. Using a mixed-methods approach that includes surveys and interviews with Gen Z consumers, the research compares levels of trust, engagement, and perceived authenticity across platforms. Findings reveal that while all platforms contribute to purchase influence, the effectiveness varies based on content type, influencer credibility, and user interaction patterns. The study also highlights the role of micro-influencers in driving niche engagement and brand loyalty. These insights offer valuable implications for marketers aiming to design platform-specific influencer strategies and for researchers exploring the evolving interplay between digital media and consumer psychology.