Abstract: The emergence of social media platforms has profoundly transformed the marketing landscape for Fast MovingConsumerGoods (FMCG) brands, positioning influencer marketing as an essential promotional strategy. This study investigates thefactorsthataffect influencer marketing in shaping the purchase decisions of consumers regarding fast-moving consumer goods inChennai.Theprocess of purchasing FMCG involves a systematic approach characterised by five distinct stages: the recognition of needs, thesearchforinformation, the evaluation of alternatives, the decision to purchase, and the subsequent behaviour following the purchase. Thisstudyiscategorised as descriptive, with a total of 154 respondents participating in the survey conducted in Chennai. The respondentsareselectedusing the convenience sampling method. The study instrument utilised is a questionnaire. The application of exploratoryfactoranalysisserves to identify the various factors that influence influencer marketing and its role in shaping the purchasing decisions of consumerswithin the FMCG sector. The calculated value of Cronbach's alpha is 0.841. The data analysis is performed using SPSSversion26.Thefactors that influence the effectiveness of influencer marketing on consumer purchasing decisions regarding fast-movingconsumergoodsinclude attractiveness, expertise, content quality, engagement and authenticity. This study contributes to the existing bodyof knowledgeon consumer behaviour by integrating aspects of influencer marketing into the decision-making framework specific tothefast-movingconsumer goods sector. This research outlines the managerial implications, emphasising strategies for fast-moving consumer goods brands to forge influencer partnerships that bolster trust, engagement, and purchase loyalty within urban Indian consumer segments.Keywords: Influencer marketing, FMCG, consumer decision-making, social media. Chennai, brand trust, purchasebehaviour