This study examines the structural relationship between brand authenticity, behavioral engagement, and willingness to pay a premium (WTP) in the B2B exhibition context of the Seoul Café Show. Unlike prior research centered on B2C markets, this study highlights three dimensions of brand authenticity―sustainability, reliability, and honesty―and their influence on exhibitors’ WTP. Survey data from 133 participating firms were analyzed using exploratory and confirmatory factor analyses, followed by PLS-SEM. The results show that brand authenticity positively affects behavioral engagement and exerts a strong direct effect on WTP. The mediating role of engagement is marginally significant, indicating that consistent identity, reliability, and honesty are more decisive for WTP than symbolic brand attributes in B2B exhibitions.