Effects of sport celebrity personality on brand image, brand identity and trust in social media: the moderating role of athlete–brand congruence

Purpose Based on the parasocial interaction theory (PSI), this study examines how the multi-dimensional personality attributes of sports celebrities on social media influence endorsed brand image, brand identity and brand trust, which further impact consumers' brand advocacy behavior. This study uses brand image and brand identity as mediator variables and celebrity-brand congruence as a moderator variable. Design/methodology/approach This study collected data from 401 individuals with high social media usage. Covariance-based structural equation modelling and Process Macro techniques are used for analysis. Findings The findings revealed that sports celebrities' social media personality attributes significantly enhanced endorsed brand image, brand identity and brand trust. Brand image exerted both direct and indirect positive effects on brand trust, which subsequently drove consumers' brand advocacy. Contrary to expectations, brand identity did not mediate brand trust. Furthermore, athlete–brand congruence negatively moderated the relationships between athlete personality attributes and brand image, identity and trust, indicating diminishing endorsement effectiveness when perceived congruence became excessively high in parasocial endorsement contexts. Originality/value This study advances celebrity endorsement literature by applying PSI to explain diminishing returns of athlete–brand congruence in social media contexts. It uniquely demonstrates that stronger congruence can weaken brand image, identity and trust, and distinguishes symbolic brand outcomes from trust-driven advocacy mechanisms.