Nowadays, rejuvenation of Chinese time-honored brands, a symbol of Chinese traditional culture, is manifested in their co-branding with new brands. With focus on sincerity and excitement, two fundamental dimensions of brand personality, the authors explore this co-branding strategy which remains unexplored by the extant literature. Based on the integration of brand personality and Stereotype Content Model, a new mechanism is constructed from the perspective of consumers, with brand admiration being the underlying mechanism, as well as product category—hedonic vs. utilitarian—being a boundary condition. Through three experimental studies, the results show that the exciting (vs. sincere) personality of new brands increases consumers' admiration for both allied brands, which in turn enhances co-branding evaluations, and that the advantage of the exciting personality holds for the hedonic co-branded product, but disappears for the utilitarian one. The research contributes to the co-branding literature and provides implications for brand partner selection and co-branded product design.