This thesis explores how fast fashion brands leverage influencer marketing on TikTok to drive consumer engagement, urgency, and impulse purchasing behavior. Through a qualitative content analysis of 320 TikTok videos related to Zara, Brandy Melville, and Shein, this study identifies the visual, textual, and emotional strategies used by influencers to promote fast fashion. The findings reveal that scarcity marketing, aspirational storytelling, and sensory-driven content - especially in haul and unboxing videos - are central tactics for triggering consumer desire and encouraging frequent, often impulsive purchases. Influencers also serve as brand intermediaries, shaping audience perceptions through personal narratives and trust-based relationships, blurring the lines between entertainment and advertising. TikTok’s algorithm and commerce tools further amplify these strategies, creating a seamless environment for trend-driven consumption. While influencer marketing is shown to be highly effective in cultivating brand loyalty and social proof, viewer comment sections also reveal tensions around body image, financial burden, and inclusivity. This study contributes to emerging conversations around the psychological and societal effects of fast fashion advertising on digital platforms, offering insights for scholars, marketers, and ethically minded consumers. Future research should further investigate the neurological and behavioral effects of sensory and urgency-driven influencer content, particularly among Gen Z audiences.