This paper examines the impact of public financial management (PFM) reforms on executing Afghanistan’s development budget. The key reforms analyzed include the AFMIS, TSA, MTBF, PBB, Public Investment Management Framework (PIMF), budget decentralization, centralized reporting systems, development budget framework, procurement process reforms, and cash management practices reform. The study is grounded in principal-agent, New Public Management (NPM), and institutional theory and employed an ex post facto descriptive, mixed-methods research design. The findings reveal a statistically positive relationship between PFM reforms and the development budget execution rate. Nonetheless, major challenges such as political and security instability, limited institutional capacity, and corruption hinder progress. Low execution rates of the development budget are further affected by line ministries' limited absorption capacity, delayed donor disbursements, and overly optimistic budget projections.