Purpose: This study examines a moderated moderation model in which the hardiness of chief marketing officers (CMOs) moderates the relationship between CMOs' future focus and firms' sustainability marketing commitment (SMC), and this moderating effect is moderated by CMOs' proactive personality. Design/methodology/approach: A sample of 298 CMOs of firms in Vietnam was surveyed to collect data. Confirmatory factor analysis was employed to validate the measures of the constructs used in the model and structural equation modeling (SEM) was used to test the model and hypotheses. Findings: The SEM results reveal that CMOs' future focus had a positive relationship with firms' SMC. Furthermore, both CMOs' hardiness and its interaction with CMOs' future focus had positive effects on firms' SMC. Finally, the three-way interaction between CMOs' future focus, hardiness and proactive personality had a positive effect on firms' SMC.Practical implications: The study findings assist firms in emerging markets in understanding the roles of some key personality-based resources of CMOs in fostering firms' SMC. Originality/value: This study is among the first to investigate the roles of CMOs' personality-based resources (i.e. future focus, hardiness and proactive personality) in firms' SMC, offering insight into the sustainability marketing literature.