ImportanceThe persistent stigma associated with mental health conditions is a major challenge worldwide. Celebrities may improve this by openly discussing their own mental health issues, potentially influencing public attitudes and encouraging individuals to seek treatment for these conditions.ObjectiveTo evaluate the impact of celebrity mental health disclosures on the incidence and prevalence of panic disorder diagnosis in South Korea.Design, Setting, and ParticipantsThis cohort study included the entire South Korean population from January 2004 to December 2021, as reflected in the National Health Insurance Service data. Analysis was conducted from May 2022 through January 2024.ExposureTime periods analyzed included the timeframe before (from January 2004 to December 2010) and after the public disclosures of panic disorder by 3 high-profile Korean celebrities between December 2010 and January 2012 (from January 2011 to December 2021).Main Outcomes and MeasuresMonthly incidence and prevalence of panic disorder, defined by the presence of a clinical diagnosis of the condition. Trends were assessed using interrupted time series analysis with autoregressive integrated moving average models. To assess public interest in panic disorder, trends in search data were analyzed, examining the association between the timing of increased searches and changes in the incidence and prevalence of panic disorder. Data on obsessive-compulsive disorder (OCD) were included as a control.ResultsThe study covered the entire population of South Korea, including 48 559 946 individuals in January 2004 and 52 593 886 individuals in December 2021. Before 2011, the mean (SD) annual prevalence of panic disorder was stable at 560 (140) persons per 100 000 persons per year. The celebrity disclosure in December 2010 was associated with higher monthly incidence rates of panic disorder, as measured by insurance claims data, changes that were observed in both the level (5.8 persons; 95% CI, 2.2-9.5 persons) and slope (0.78 persons per month; 95% CI, 0.19-1.40 persons per month) per 100 000 persons. By 2021, the observed annual prevalence per 100 000 persons reached 7530 persons, an increase of 775.6% compared with the 860 persons (95% CI, 330-1400 persons) estimated if the disclosures had not occurred. Internet searches anticipated changes in monthly prevalence with a lag of 2 or 3 months (F = 4.26, P = .02 and F = 3.11, P = .03, respectively). The celebrity disclosures had no significant association with the incidence or prevalence of OCD.Conclusions and RelevanceIn this observational cohort study, celebrity disclosure of mental health conditions was associated with a sustained reduction in stigma, as reflected in increased help-seeking behavior for the condition over more than a decade. This underscores the influential role celebrities can play in shaping public health perceptions and behaviors, offering valuable insights for the development of future mental health policies and public awareness campaigns.