Sponsorship Disclosure on Instagram: A Systematic Review of Research from 2020 to 2025

Research on sponsorship disclosure in social media influencer marketing has grown rapidly, yet findings remain inconsistent. This study reviews 37 articles published between 2020 and 2025 to identify the main factors shaping consumer responses to disclosure. The analysis draws on experiments, surveys, qualitative studies, and computational approaches, focusing primarily on Instagram but also considering other platforms. Results show that disclosure outcomes depend on mechanisms such as persuasion knowledge, transparency perceptions, and parasocial relationships, as well as on message design, audience characteristics, and cultural context. While disclosures often lower short-term engagement and brand attitudes, they can strengthen trust and credibility over time. The review highlights key gaps, including reliance on short-term experimental designs, limited cross-cultural perspectives, underrepresentation of platforms, focusing only on Instagram, and insufficient attention to algorithmic barriers.