This study examines how influencer marketing shapes the buying behaviour of Young Adults (18-35) through netnographic observation. It examines the influence of Instagram-based micro-and macro-influencers on the buying decisions of Young Adults in the fashion domain. This study synthesises three important frameworks: Parasocial Interaction (PSI), the Elaboration Likelihood Model (ELM), and Social Interaction Theory (SIT). It has used a secondary data approach employing netnographic analysis of 60 active micro-influencers and 60 active macro-influencers from Instagram over a period of two months. These 120 accounts were studied by analysing their Stories, Posts, Captions, Reels, Comments and Engagement patterns. The findings suggest that micro-influencers generate higher levels of purchase intent among the target group of Young Adults (18 – 35 years), largely due to perceived trust, authenticity, and relational closeness. The inferences of this study extend beyond marketing practice and delve into the sociology of digital culture, the persuasion process, and the psychology of consumer intentions and decisions