By pioneering a comprehensive analysis of lean integration within the construction sector, this research provides novel insights into optimizing project outcomes. The construction industry is generally known for its frequent deadline slip-ups, budget overruns, and issues with upholding proper quality. It is usual practice to integrate different management techniques which are successful in the production industry in order to avoid such issues. Several researchers adopted sustainable construction management, lean management and alliance contract practices individually on construction sites to improve the profit, productivity, quality and transparency of the project. In this study, the synergetic integration of sustainable construction management, lean management and alliance contract practices have been studied. A questionnaire survey was conducted among 345 practitioners, resulting in 309 responses after screening. These respondents, comprising various roles in the AEC sector, provided insights into their experience, project involvement, and business sectors. The study identified 23 factors associated with lean practices, sustainable construction, and alliance contracts, examining their relationships and benefits through Structural Equation Modeling (SEM). The results demonstrate significant effects of lean practice, sustainable construction, and alliance contract factors on the benefits derived from their integration. Measures of reliability and validity affirm the robustness of these relationships. The discussion underscores the benefits of integration, including enhanced efficiency, reduced environmental impact, improved collaboration, shared risk and reward, superior project outcomes, and competitive advantage. Overall, this research elucidates the potential advantages of integrating these methodologies within construction projects.