The objective of this paper is to understand the extent to which Lean Management techniques are improving overall productivity and project performance at Construction and Engineering Company, one of the major construction companies in Oman. In addition, it studies how leadership dedication influences the efficacy of Lean Management, using the speculative hypothesis that leadership dedication increases the impact of Lean efforts. Moreover, the research is based on pragmatic philosophy as a mixed-method study. The study was a 32-item questionnaire with three open-ended questions and included 65 employees at the firm. Descriptive and correlation analyses were used to evaluate quantitative information; thematic analysis was used for qualitative answers to understand how people felt about Lean Management and confirm quantitative information. The study results demonstrate that leadership engagement, strategic alignment, and employee engagement are the most significant factors in improving operational and project performance. Determinant leadership and alignment with strategic priorities were also highlighted as crucial to successful Lean implementations, as was the involvement of employees. The research is only conducted in one case in Oman, but its findings can inform other research in similar settings. Furthermore, the research offers practical lessons for the construction and engineering industry that demonstrate the need for leadership commitment, strategic alignment and employee engagement to make Lean Management initiatives successful. These findings illustrate the possibilities of Lean Management for enhancing business efficiency and project performance in Oman-based construction companies and similar industry sectors.