Enhancing advertising novelty through celebrity cameo endorsement

Celebrity endorsement is a widely used tool in strategic marketing, yet questions remain about how to enhance its novelty and ad effectiveness. We introduce and test a novel executional tactic: celebrity cameo endorsement: a brief appearance by a new known figure alongside an existing, long-standing brand endorser (e.g. John Malkovich alongside George Clooney for Nespresso). Across two experiments and a Google Trends analysis, we find that celebrity cameo endorsements featuring strong/equal-capital celebrities (i.e. with comparable or higher media visibility to the primary endorser) increase ad novelty and improve search interest, purchase intention, and actual purchase behavior. In contrast, weaker-capital cameo endorsers reduce ad novelty and undermine campaign effectiveness. These findings highlight the importance of a strong foundational endorsement when layering in additional celebrity figures. We offer actionable guidance for advertisers seeking endorsement strategies that are both novel and coherent while enhancing consumer engagement.