Influencer Marketing Transparency and Consumer Response: The Effect of Sponsorship Disclosure on Trust, Brand Attitude, and Purchase Intention

The rapid expansion of social media has fundamentally reshaped how brands communicate with consumers, making influencer marketing one of the most commercially significant advertising formats of the digital age. Yet, as sponsored content increasingly blends into organic posts, the question of commercial transparency has become both a regulatory imperative and a scholarly concern. Despite growing academic interest, the existing literature remains fragmented: studies examining sponsorship disclosure effects tend to address persuasion knowledge activation, source credibility, or behavioral outcomes in isolation, without proposing an integrative framework that connects these mechanisms into a coherent explanatory chain. In particular, the mediating role of consumer trust , namely the psychological mechanism through which disclosure shapes brand attitude and purchase intention, remains insufficiently theorized. This article addresses this gap by developing an integrated conceptual framework that articulates four complementary theoretical perspectives: the Persuasion Knowledge Model, Source Credibility Theory, Parasocial Identity Theory, and the Theory of Planned Behavior. It is worth clarifying from the outset that this contribution is integrative in nature rather than theory-generative in the strict sense. The originality of the proposed framework lies not in the introduction of new theoretical concepts, but in the way existing and complementary frameworks are assembled to produce explanatory predictions that none of them could yield individually. Drawing on a structured narrative literature review guided by a PRISMA-inspired protocol, for which a complete selection flow is provided, the study identifies 187 initial records that were progressively filtered through duplicate removal, abstract screening, and full-text eligibility assessment, yielding a final corpus of 32 articles. the study proposes a processual model in which sponsorship disclosure acts as a signaling mechanism that shapes consumer trust, which in turn drives brand attitude and purchase intention. The moderating role of influencer type, whether micro or macro, is also incorporated into the model. Six research hypotheses are formally stated and theoretically grounded. This research contributes to the influencer marketing literature by offering a unified theoretical framework, reconciling contradictory empirical findings, and opening concrete avenues for future empirical validation, particularly in emerging market contexts, and more specifically in the Moroccan context, where the influencer marketing sector has expanded considerably since 2018 yet continues to operate without a dedicated regulatory framework governing sponsorship disclosure, and where the dynamics of consumer trust in digital advertising remain largely unexplored in the existing literature.