In today’s project environment, significant changes are taking place, prompting a shift in project management knowledge from a traditional process oriented approach to one that is principle and performance based, allowing for more flexible application across diverse industry contexts. This study empirically examines the impact of four key knowledge areas from the PMBOK (Project Management Body of Knowledge) stakeholder management, planning management, project work management, and delivery management on both project performance and corporate performance. The research focuses on the construction industry as the target sector and additionally analyzes whether project size and company size function as moderating variables. The results indicate that a higher level of maturity in the key knowledge areas leads to improved project and corporate performance, with such positive effects being particularly pronounced in large scale projects and large enterprises. In the construction industry, in particular, the four knowledge areas were found to be closely associated not only with project performance but also with non-financial corporate performance indicators such as customer satisfaction, customer loyalty, and corporate image.