Predictors of social media influencer marketing effectiveness: A comprehensive literature review and meta-analysis

• Tackling the fundamental question on what drives influencer effectiveness. • Literature review and meta -analysis of 93 papers on predictors of effectiveness. • Literature synthesis to reveal and resolve conflicts in existing research findings. • Creating a holistic framework to predict influencer effectiveness. Following an increased research focus on influencer marketing and social media influencers (SMIs) in recent years, marketers continue to face the critical challenge of selecting effective SMIs for their campaigns. This difficulty is compounded by the fact that much empirical research is based on single-theory approaches, offering limited predictors and hindering the development of broad practical and theoretical insights. To address this gap, this paper aims to provide a comprehensive and structured overview of predictors of SMI marketing effectiveness through both qualitative and quantitative analysis. Based on a review of 93 articles, covering 108 studies, 56 predictors, and seven dependent measures of SMI marketing effectiveness, this paper introduces a generalized framework for SMI marketing effectiveness and confirms 11 predictors of customer engagement and seven of purchase intention, which are both key measures of effectiveness, clarifying previously inconsistent findings.