Anti-stigma campaigns increasingly leverage personal narratives of celebrities or public figures through social media, yet little is known about what makes social media an effective storytelling tool. This study empirically tests their mental health stories in different media formats using a multiple message design. Through a pilot study, four celebrities were selected: Kristen Bell, Mariah Carey, Dwayne Johnson, and Kevin Love, who have disclosed their mental health struggles. An online between-subjects experiment was conducted with 389 participants who were randomly assigned to one of three conditions (social media vs. online article vs. no-message control). Results showed that participants who read the stories in a social media format felt a greater social presence, as if they were engaging in a real conversation with the celebrity, compared to those who read the same stories in an online article format. This, in turn, facilitated a stronger sense of transportation into the story, ultimately leading to persuasive outcomes such as positive attitudes toward help-seeking and increased intentions to seek both professional and informal help. Further analyses revealed that the effects of social presence and transportation on attitudes toward help-seeking were more pronounced among those with greater parasocial intimacy with the celebrity. The findings provide empirical support for the effectiveness of using social media as a storytelling channel for anti-stigma campaigns.