Based on persuasion knowledge theory, attribution theory, and a qualitative investigation of authenticity, this study investigates employees' CSR authenticity evaluation in four CSR domains (customer-, employee-, environment-, and philanthropy-oriented). Four antecedents of employees' CSR authenticity evaluation are examined: the evaluation of CSR advertising, the perceived fit between corporate culture and CSR engagement and two perceived CSR motives. Additionally, employees' involvement in CSR as an individual difference variable is analyzed. Results are reported from a study with the employees (n = 432) of a large European energy provider. Findings reveal that the evaluation of the CSR advertising and the perceived corporate culture fit have a higher impact on employees' CSR authenticity evaluation than do the perceived CSR motives. While CSR authenticity in the customer-, employee- and environment-oriented CSR domain are mainly influenced by perceived corporate culture fit, CSR authenticity in the philanthropy-oriented CSR domain is mainly affected by the evaluation of CSR advertising. Display omitted •Corporate culture fit and ad evaluation are vital for employees' CSR authenticity evaluation.•Perceived company motives are less relevant.•Involvement in CSR moderates these relationships.•Four CSR domains (customer, employee, environment, philanthropy) are investigated.•Real-world dataset was gathered from a large European energy provider.