Influence unveiled: examining sponsorship disclosure in influencer marketing through moderated serial mediation and MGA across PSRs and generational differences

Purpose This study explores the impact of sponsorship disclosure on purchase intention, focusing on the serial mediation of brand attitude and source credibility and the moderating roles of generation (Gen Y and Gen Z) and parasocial relationships. Design/methodology/approach A survey tool was distributed to social media users of Facebook and Instagram who follow at least one social media influencer and have previously engaged in promotional content from the influencers. A total of 553 responses were analyzed through partial least squares (PLS) multigroup analysis using PLS-structural equation modeling (SEM) while moderating effects were examined using PROCESS macro in SPSS. Findings Results indicate that sponsorship disclosure negatively affects brand attitude and source credibility, lowering purchase intention, while strong parasocial relationships mitigate this effect. Brand attitude and source credibility jointly mediate the relationship between disclosure and purchase intention. Gen Z perceives disclosures as transparent and authentic, enhancing receptiveness, whereas Gen Y is more skeptical. Practical implications The study possesses valuable insights for brands, marketers and policymakers to optimize influencer campaigns. Findings suggest that brands should design transparent yet strategically framed disclosures, prioritize credible influencers and foster strong parasocial relationships to mitigate negative disclosure effects and enhance consumer engagement. Originality/value This study is among the first to integrate sponsorship disclosure, brand attitude, source credibility, generational differences and parasocial relationships within the framework of the elaboration likelihood model. By simultaneously examining serial mediation and moderation and integrating multiple theoretical perspectives, this study provides a comprehensive understanding of how sponsorship disclosure influences purchase intention and offers new insights for enhancing influencer marketing effectiveness.