This cohort study investigated associations of nonalcoholic fatty liver disease (NAFLD) and metabolic dysfunction–associated fatty liver disease (MAFLD) with risk of increase in arterial stiffness (AS), measured as brachial-ankle pulse wave velocity (baPWV). Participants who had health examinations between 2006 and 2019 were analyzed for fatty liver and increased baPWV using liver ultrasonography and automatic volume plethysmography device. Participants were classified based on presence of MAFLD or NAFLD and further divided into subgroups: no fatty liver disease (reference), NAFLD-only, MAFLD-only, and both NAFLD and MAFLD. Subgroups were additionally stratified by sex. Cox proportional hazard model was utilized to analyze the risk of developing baPWV ≥1400 cm/s in participants without baseline elevation of the baPWV. The NAFLD and MAFLD groups exhibited higher risks of increased baPWV (NAFLD: adjusted hazard ratio (aHR), 1.35 95% CI, 1.29–1.42; MAFLD: aHR, 1.37 95% CI, 1.31–1.43) compared to group without the conditions. Incidence of NAFLD or MAFLD were higher in men than in women but aHR of developing the increase in AS was higher in women. In subgroup analysis, the MAFLD-only group presented the strongest associations with increase in AS (aHR, 1.53 95% CI, 1.43–1.64), with the trend more pronounced in women than in men (Women, aHR, 1.63 95% CI, 1.08–2.46; Men, aHR 1.45 95% CI, 1.35–1.56). Both NAFLD and MAFLD are significantly associated with elevated AS. These associations tended to be stronger in MAFLD than in NAFLD, in women than in men. •We analyzed 122,726 Korean population with health examination data from 2006 to 2019.•NAFLD and MAFLD are related to the risk of increased arterial stiffness measured by baPWV.•The numerical association was modestly more pronounced in MAFLD-only than in NAFLD-only, and in women than in men.