Poor performance in executive functions is observed in individuals with eating disorders (EDs). These impairments have usually been associated with the presence of comorbid psychopathology or with higher severity of EDs. However, few studies have explored the interaction between illness duration and deficits in executive functions. The present study investigates the association between ED duration and performance in decision-making, inhibitory control, and cognitive flexibility in the anorexia nervosa restrictive subtype (AN-R), bulimic/purging subtype (AN-BP), and binge spectrum disorders (BSDs) (namely, bulimia nervosa and binge eating disorder) among 116 women with EDs compared with 123 women healthy controls (HCs). Using cumulative survival analysis, we estimated the risk of deficits related to illness duration. Predictors of executive dysfunctions were assessed by regression analysis, including as potential predictors illness duration, severity of general psychopathology, and ED symptomatology. Results showed poor decision-making and cognitive flexibility in participants with EDs compared with HCs. ED duration was associated with poor inhibitory control in the AN-BP group and poor cognitive flexibility in the BSD group. The illness duration increased the risk of presenting early deficits in executive function. In decision-making and inhibitory control, the AN-R group showed the earliest deficits, whereas in cognitive flexibility it was the BSD group. ED duration predicted impaired cognitive flexibility in the BSD group and impaired inhibitory control in the AN-BP group, whereas the severity of general psychopathological symptoms was a predictor of impaired cognitive flexibility in individuals with AN-R. These results highlight the relevance of illness duration in executive dysfunctions in EDs.