Through a case study of the Irish Health Service Executive’s (HSE) response to a fake news attack on their HPV vaccination campaign, we argue that responses to fake news should be analyzed from a legitimacy perspective. We propose a model of emotion legitimacy management where the HSE and a third-party collaborated to: (1) connect with the emotional aspects of the issue, (2) leverage emotions to build vicarious legitimacy, (3) transfer the third-party's legitimacy to the organization, and (4) activate the target public emotionally. This study contributes to the field of fake news and legitimacy management by moving beyond fact-checking and debunking strategies. We suggest a framework centered on legitimacy and organizational agency in using emotions to counteract fake news. Finally, we emphasize the importance of third-party vicarious legitimacy building and its transfer to the organization.