Social media platforms have increasingly evolved into commercial environments where consumption is integrated into everyday user practices. TikTok has emerged as a prominent arena for social commerce, in which influencers play a central role in shaping consumers’ purchase decisions. The purpose of this study is to explore the motivational factors influencing young adults’ purchase decisions in TikTok shopping within a Western context, with particular emphasis on perceived influencer authenticity and the interaction between social and individual drivers.The study adopts a qualitative research approach and is based on two focus group interviews with a total of nine women aged 18–30 who had previously made purchases via TikTok. The data were analyzed using thematic analysis to identify recurring patterns and key themes in participants’ discussions.The findings indicate that perceived influencer authenticity, credibility, and relatability are central factors influencing purchase decisions. Social drivers such as recommendations, parasocial relationships, and social validation interact with individual motivations including convenience, inspiration, and perceived value. The results also suggest that the boundary between entertainment and commercial content on TikTok is perceived as blurred, which affects how marketing messages are interpreted and internalized by consumers.This study contributes to a deeper understanding of consumer behavior in social commerce and highlights the importance of influencer authenticity as a key driver of purchase decisions among young adults on TikTok.