Influencer beware: The buffering role of sponsor–influencer fit in the commercialization-authenticity trade-off

As social media influencers (SMIs) increasingly commercialize their online presence through sponsored content, understanding how sponsorship intensity shapes consumer responses has become important. Drawing on attribution and congruence theories and the entity-referent correspondence (ERC) framework, this study examines how sponsorship levels influence audience engagement and purchase intentions through perceived personal authenticity (PPA) and whether these effects depend on sponsor–SMI fit. Three experimental studies were conducted to test the proposed relationships. The results show that higher sponsorship levels reduce consumers’ intention to follow influencers and share their content. Sponsor–SMI fit attenuates the negative effect of sponsorship intensity on PPA. Thereby mitigating its adverse effects on consumer engagement and purchase intentions. We further demonstrate that sponsorship level affects consumer responses indirectly through PPA and that this indirect effect is contingent on sponsor–SMI fit. These findings advance the influencer marketing literature by applying the ERC framework to distinguish the different authenticity types and their impact on consumer behavior. The study also extends attribution and congruence theories by explaining how and when commercialization influences consumer responses and offers practical guidance for balancing monetization and authenticity in influencer marketing.