Unethical Influencer Marketing: A Systematic Review and Research Agenda

ABSTRACT Social media influencer (SMI) marketing has revealed substantial regulatory gaps and problematic behaviors threatening consumer welfare. This systematic literature review examines 83 high‐quality articles (ABS 3–4★ and SJR Q1–Q2 journals, 2016–2025) using the Theory–Context–Characteristics–Methodology (TCCM) framework. Our analysis identifies critical dark‐side practices: undisclosed sponsorships—with Ershov et al. in 2025 documenting 96% nondisclosure in their analysis of 100+ million Twitter posts; counterfeit endorsements (Shepherd et al. in 2023 found 22% of UK consumers purchased counterfeits following influencer recommendations); misinformation dissemination; and harmful content promotion. Findings reveal theoretical fragmentation with Source Credibility Theory (21 studies) and Parasocial Relationship Theory (14 studies) dominating, while 34% lack explicit frameworks. Geographically, research concentrates in Western economies (United States 47%, Europe 35%), with Africa and Latin America unrepresented. Methodologically, quantitative approaches predominate (75%), yet cross‐sectional designs limit causal inference. Critical gaps persist in examining regulatory enforcement, platform accountability, consumer vulnerability, and actual behavioral outcomes. This review provides actionable insights for policymakers, platforms, and researchers fostering ethical influencer marketing practices.