The increasing use and effectiveness of social media influencers in marketing have intrigued both academic scholars and industry professionals. To shed light on the foundations and trends of this contemporary phenomenon, this study undertakes a systematic literature review using a bibliometric-content analysis to map the extant literature where consumer behavior, social media, and influencer marketing are intertwined. Using 214 articles published in journals indexed by the Australian Business Deans Council (ABDC), Chartered Association of Business Schools (CABS), and Web of Science (WOS) from 2008 to 2021, this study unpacks the articles, journals, methods, theories, themes, and constructs (antecedents, moderators, mediators, and consequences) in extant research on social media influencer marketing. Noteworthily, the review highlighted that the major research streams in social media influencer marketing research involve parasocial interactions and relationships, sponsorship, authenticity, and engagement and influence. The review also revealed the prominent role of audience-, brand-, comparative-, content-, influencer-, social-, and technology-related factors in influencing how consumers react to social media influencer marketing. The insights derived from this one-stop, state-of-the-art review can help social media influencers and marketing scholars and professionals to recognize key characteristics and trends of social media influencer marketing, and thus, drive new research and social media marketing practices where social media influencers are employed and leveraged upon for marketing activities.