Vietnam has sustained one of Southeast Asia's most remarkable economic trajectories over the past three decades, driven in significant part by deliberate macroeconomic policy reforms. However, the precise mechanisms linking macroeconomic policy to sustained economic growth—particularly the mediating role of institutional quality—remain underexplored in the Vietnamese context. This study investigates the relationships among macroeconomic policy pillars (state investment, foreign direct investment attraction, monetary stability, and fiscal discipline), institutional quality, and economic growth in Vietnam over the period 2010–2023. Using structural equation modelling (SEM) and bootstrapping with provincial-level data from 30 provinces and 420 respondents comprising government economists, policy analysts, and enterprise managers, the study finds that: state investment, FDI attraction, and monetary stability each significantly and positively predict economic growth outcomes; fiscal discipline strengthens overall macroeconomic stability; and institutional quality mediates the macroeconomic policy–economic growth nexus. These findings contribute a developing-country perspective to fiscal federalism and macroeconomic governance literature, and carry direct implications for Vietnamese policy formulation.