The role of capital budgeting in investment decision-making across countries has become increasingly critical as firms operate within diverse economic, institutional, and regulatory environments. Techniques such as Net Present Value (NPV), Internal Rate of Return (IRR), and Payback Period are used to support rational, value-maximizing decisions; however, their application varies significantly across countries due to differences in financial development, governance, and managerial capability. This study examines how capital budgeting practices influence investment decision-making and identifies key factors shaping their implementation using a Systematic Literature Review (SLR) of 34 peer-reviewed articles published between 2021-2026. The findings reveal substantial variation in the adoption and sophistication of techniques, with firms in developed countries applying more advanced, risk-adjusted methods, while those in developing countries rely on simpler approaches due to resource and knowledge constraints. Behavioral factors, such as managerial overconfidence and risk perception, also influence decisions and may lead to suboptimal outcomes. Institutional quality, corporate governance, and financial literacy further determine effectiveness. This study concludes that while capital budgeting plays a crucial role, its effectiveness is highly context-dependent and shaped by both technical and behavioral factors.