Background: Transformational leadership is increasingly recognised as a key determinant of employee outcomes in organisational settings. Despite growing interest, a systematic synthesis of its concurrent effects on employee performance and counterproductive work behaviour (CWB) remains limited.

Objective: This review examines how transformational leadership influences employee performance and CWB, and identifies key mediating and moderating factors. Methods: Following PRISMA 2020 guidelines, three databases (SciSpace, Google Scholar, PubMed) were searched. After screening 611 records, 152 studies met inclusion criteria.

Results: Evidence consistently shows that transformational leadership positively predicts employee performance and negatively predicts CWB. Psychological empowerment, job satisfaction, organisational commitment, and trust are prominent mediators.

Conclusions: Transformational leaders enhance performance and curb deviant behaviour through multiple psychological and social pathways. Future research should address cultural variation and longitudinal designs.