This study examines the effect of irrelevant information presented in marketing communications by a celebrity co-branding partner on consumer judgments of a partner brand. Three experimental conditions manipulate the relevancy of information: relevant information, irrelevant information, and relevant plus irrelevant information. Findings from this study suggest that when a celebrity co-branding partner does not provide information about the partner brand nor brand benefits, consumer judgments in the ability of the partner brand to deliver benefits, their purchase intent and their match-up perceptions become less positive. Consumer brand benefit beliefs and purchase intentions show evidence of a dilution effect only when consumers perceive a mismatch between the celebrity and brand and when presented with irrelevant information supplied by a celebrity in addition to relevant brand information. Interestingly, not only the relevant celebrity characteristics associated with the brand but also the irrelevant information provided by the celebrity in the advertisement influence perceptions of match-up or congruence. Brand managers should ensure a celebrity co-branding partner does not provide irrelevant brand information within advertisements to avoid brand benefit belief, purchase intent and match-up dilution.