Influencer Marketing in the Digital Economy: A Critical Review of Theoretical Foundations, Global Trends, and Emerging Transformations

Abstract

Influencer marketing has become a defining feature of the contemporary digital economy, fundamentally reshaping how brands communicate with consumers through socially embedded digital creators and platform-mediated interactions. Although the field has expanded rapidly across marketing, communication, psychology, and media studies, its theoretical development remains fragmented, with existing research predominantly relying on isolated explanatory perspectives to examine credibility, engagement, parasocial interaction, social learning, and consumer behaviour. This study addresses this conceptual limitation through a critical, integrative, and theory-building review of the influencer marketing literature. Drawing upon a comprehensive synthesis of scholarly research and recent developments in digital platforms, creator economies, algorithmic governance, and social commerce, the review critically evaluates the evolution of influencer marketing from celebrity endorsement to an adaptive socio-technical ecosystem. Building upon this synthesis, the study develops Adaptive Digital Influence Theory (ADIT) as an integrative middle-range framework that reconceptualises digital influence as a recursive, adaptive, and platform-mediated process emerging from the interaction of adaptive credibility, relational engagement, algorithmic mediation, adaptive co-evolution, and behavioural feedback. By integrating previously fragmented theoretical traditions within a unified explanatory architecture, ADIT extends the conceptual boundaries of influencer marketing research while providing a coherent foundation for future empirical investigation. The review concludes that understanding influencer marketing requires a shift from linear models of persuasion towards adaptive systems of digital influence, thereby contributing to the theoretical advancement of influencer marketing, digital marketing, platform studies, and consumer behaviour research.