Several reports show a significant association between metabolic dysfunction-associated steatotic liver disease (MASLD) and arterial stiffness (estimated pulse wave velocity [ePWV]) as a surrogate marker of vascular age. We investigate whether ePWV as arterial stiffness in MASLD is associated with all-cause/cause-specific mortality. This cohort study was based on the third National Health and Nutrition Examination Survey (NHANES, 1988-1994) and NHANES 2007-2014 and linked mortality datasets through 2019. Cox regression models assessed the association between ePWV categorized by quartile and all-cause/cause-specific mortality among individuals with MASLD. During the follow-up of a median of 26.3 years (interquartile range: 19.9-27.9), higher levels of ePWV among individuals with MASLD were associated with increased all-cause mortality, which remained significant after adjusting for demographic, lifestyle, clinical, and metabolic risk factors. Furthermore, higher ePWV in MASLD was associated with higher cardiovascular mortality. There was a 44% (hazard ratio: 1.44, 95% confidence interval: 1.32-1.58) increase in all-cause mortality and a 53% (hazard ratio: 1.53, 95% confidence interval: 1.32-1.77) increase in cardiovascular mortality for every 1 m/s increase in ePWV in MASLD. However, there was no significant association between ePWV and cancer-related mortality. Sensitivity analyses using the NHANES 2007-2014 dataset showed results identical to the original analysis. Higher ePWV in MASLD was associated with a higher risk of all-cause and cardiovascular mortality beyond traditional cardiovascular risk factors. Screening for ePWV in individuals with MASLD may be an effective and beneficial approach to reducing all-cause and cardiovascular mortality.