This study examines the moderating effect of perceived environmental uncertainty (PEU) and task uncertainty on relationships between performance management system (PMS) practices and organizational performance in Vietnam. We examine the five PMS practices codified by Ferreira and Otley's paper in 2009,adopting non-financial performance measures (NFPMs), decentralizing decision-making, lower-level manager participation in setting organizational performance targets, interactive use of NFPMs, and objectivity in performance evaluation and rewards. Employing partial least squares structural equation modelling (PLS-SEM) to analyze survey data obtained from managers of companies listed on the Vietnamese Stock Exchange, we find three PMS practices-adopting non-financial performance measures (NFPMs), decentralizing decision-making, lower-level manager participation in setting organizational performance targets-are positively associated with organizational performance. However, these positive associations are considerably malleable in the face of PEU and task uncertainty. Our finding suggests that only lower-level manager participation in setting organizational performance targets positively impacts organizational performance under PEU, whilst only decentralizing decision-making has a significant and positive effect on organizational performance under task uncertainty. The study contributes to a growing body of knowledge on the effectiveness of PMS practices for organizational performance, particularly in times of uncertainty.