Due to the lack of insight into the impact of budgeting practices at the micro-levels in emerging countries in Asia, this study examines the effect of budgetary participation on managerial performance in Vietnam. Drawing from the framework of decision-making, nomological network, and self-determination theory, this study proposes that the link between budgetary participation and managerial performance is mediated by autonomous motivation and information sharing. It is also proposed that high autonomous motivation induces information sharing. Data collected from 153 managers working in Vietnamese public schools were used to test the proposed model. The results from PLS-SEM analysis show that only information sharing mediates the relationship between budgetary participation and managerial performance, while autonomous motivation does not because data fails to support the positive relationship between autonomous motivation and managerial performance. Budget participation also leads to higher autonomous motivation, and autonomous motivation improves information sharing.