This study explores the influence of Chief Executive Officer (CEO) narcissism on the environmental, social, and governance (ESG) performance of listed firms on the Johannesburg stock market (JSE). Using hand‐collected data from annual reports and ESG rating data from the CSRHub dataset, we conducted empirical analyses for 81 firms from 2014 to 2022. As the first study to assess CEO narcissism using a validated unobtrusive measure in the South African market, the Driscoll and Kraay approach of panel corrected standard errors was employed in the main analysis, while the two‐stage least squares (2SLS) model was used for robustness. Results revealed that there is a negative and significant relationship between CEO narcissism and ESG performance. Moreover, CEO gender positively moderates the negative relationship between CEO narcissism and ESG performance. The results provide a meaningful empirical addition to the upper echelons literature by delineating the implications of the dark sides of narcissism for management, regulators, and policymakers.