Social media advertising is a novel approach to brand or goods advertising, aimed at cultivating a favourable public opinion and encouraging brand loyalty. This research looks at how loyalty to brands among millennials and Generation Z—a group that is highly engaged with technologies and social media—is affected by social media influencers. The research applied different users of Instagram from Indonesia and made a route analysis and Sobel investigated to look at the indirect impact. Testing for accuracy, dependability, and traditional presumptions was performed to ensure the information was suitable for extra examination. The findings highlighted that buying intentions may act as a mediating factor between social media experts and Millennial devotion to brands, as well as the way social platform influences can affect Generation Z and millennials’ loyalty to a brand. This study emphasizes how crucial it is to develop promotional strategies that work with millennials and Generation Z.