Social networks like Instagram are used more and more by advertisers to publicize products. Social media's dominant position in customers ' lives has driven advertisers to ramp up their displays based on the network. The study explores the effectiveness of brands' social media advertising on consumer purchasing decision-making in human hair with the mediating effect of consumer engagement in Nigeria. This research considers informativeness, interactivity, performance expectancy, and perceived relevance as variables used in describing and representing social media advertising and its influence on consumer purchasing as mediated by consumer engagement. The study utilizes the theoretical context and the theory of social exchange to analyze social media ads and integrate the idea of customer engagement with purchase intention. Quantitative methodology is followed in this study to meet research objectives. Two hundred sixty-two questionnaires were collected from Instagram users in Nigerians in this study, and data were analyzed using Statistical Package for Social Science (SPSS). The result of this study confirms the significant impact of social media advertising on consumer purchasing.