Social media platforms are increasingly important for promoting brands. Focusing on social media influencer marketing (SMIM), this study employs fuzzy set qualitative comparative analysis (fsQCA) to explore the configurations of influencer characteristics and content features sufficient for high SMIM effectiveness. The study identifies different configurations of influencer characteristics and content features that drive high likes, high favorites, and high comments on social media. It also reveals that single conditions are not necessary for high SMIM effectiveness. The existence of influencer popularity is the core condition for achieving high likes, high favorites, and high comments in many configurations. Furthermore, the study shows that diverse configurations of influencer characteristics and content characteristics lead to highly appealing SMIM, highlighting the importance of different paths to achieve the same goal. This research contributes to the understanding of social media marketing and influencer marketing, providing valuable insights for developing effective social media marketing strategies.