PurposeKnowledge is the main product of professional service firms; therefore, knowledge is the key to success. Due to the nature of this organizational type, management in professional service firms has faced many challenges in encouraging employees to share knowledge. The diffusion of technologies has facilitated technology-mediated knowledge sharing (TMKS), which helps the transfer of knowledge become easier without time and space limits. This study aims to unfold the impact of transformational leadership as an antecedent of TMKS under the interplay with perceived ease of use and perceived usefulness in using technology.Design/methodology/approachAn online survey was distributed to employees in professional service firms through the snowball sampling method. Three hundred forty employees, who had experience with technology-mediated knowledge sharing, participated in the survey.FindingsThe findings showed that transformational leadership had a significant impact on TMKS, which was moderated by perceived usefulness and gender. TMKS influenced organizational innovation, and the mediating effect of TMKS was identified.Originality/valueThis study provides solutions for management in professional service firms to motivate their employees to share knowledge via technology, which drives organizational innovation. More caution about gender differences and the low levels of perceived usefulness from employees need to be considered when adopting transformational leadership.