This study aimed to develop a stand yield table for Acacia mangium plantations in Vietnam and to analyze their economic feasibility. Field measurements were conducted across 12 temporary sample plots established in A. mangium plantations aged 1–7 years in northeastern Vietnam, using a chronosequence sampling design. Based on this, regression analyses were performed to develop stand growth models for DBH, H, SD, BA, and V. NPV measures the absolute value of the investment at a specified discount rate (4.0%, 5.5%, and 7.0%), while IRR identifies the break-even discount rate. At rotation ages of 5–7 years, IRR values are negative—a mathematically valid result arising from non-conventional cash flow structures in which Norstrom’s sign-change criterion is not satisfied; positive IRR values (~4%) are obtained from rotation age 8 onward. A sensitivity analysis confirmed that increasing yields is the most effective strategy for increasing plantation viability. This study serves as a fundamental resource for plantation projects in Vietnam and emphasizes the necessity of management improvements to create sustainable plantation operations.