This research analyses how different leadership styles affect project managers in the telecommunications sector, focusing on transactional and transformational leadership's direct effects on project performance. Ambidextrous Leadership's role as a mediator is explored alongside the influence of Project Management approaches (Waterfall, Agile, Hybrid) and Project Manager Certifications. Data from 224 Project Managers in 77 Indonesian telecom companies was examined using Structural Equation Modelling Partial Least Square (SEM PLS). The findings indicate that Transactional and Transformational Leadership alone don't directly affect Project Performance, but Ambidextrous Leadership significantly enhances it. Different Project Management Approaches (Waterfall, Hybrid, Agile) amplify the impact of leadership styles. Transactional leadership is strongly linked to the waterfall, while transformational and ambidextrous leadership aligns with the agile and hybrid approach. Project Management Certification strengthens Transactional Leadership's effect on Project Performance, with less impact on Transformational Leadership. The research emphasizes the significance of Ambidextrous Leadership in improving project performance and how project management approaches and certifications can enhance or moderate the influence of leadership styles on telecommunication project management. These findings offer industry practitioners and organizations valuable insights, contributing to leadership, project management, and telecommunications research.