This dissertation asses what Project Management Offices (PMOs) develop in the financial management aspect of modern-day organizations, focusing on key areas of cost estimation, budgeting and financial surveillance. This research investigates the way PMOs establish and use financial frameworks to enhance project and portfolio performance by using a qualitative multiple case study method in three organizations representing different sectors. It is demonstrated that mature PMOs do more than give generic support, they are crucial strategic players of controlling costs, judging investments, and the creation of value enhancement. Notable tools mentioned are Work Breakdown Structures (WBS), Cost Breakdown Structures (CBS), and Earned Value Management (EVM), which is critical in bringing traceability and financial oversight oneness. Moreover, the study highlights the ways in which digital technologies, such as SAP, Primavera, and Power BI allow immediate access to financial data. Digital tools are available but standardizing estimation processes, combining project and financial systems, and enhancing financial openness of project teams continues to be an issue. The study reinforces the concept that a successful governance structure should allow financial discipline and organizational agility at the same time. In addition to what it adds empirically, the dissertation theoretically enriches existing literature by incorporating financial considerations into mature established PMO models. In practice, considering the study, the recommendation is made to implement integrated financial systems, use flexible budgeting tools and support cooperation between PMO and finance teams. Financial governance is recognized here as a critical competency upon which the PMO relies to integrate project delivery with the larger organization strategy.