<p>This study aimed to examine the restorative effects of aerobic exercise on mental fatigue using physiological indicators. Mental fatigue was induced in healthy adults using the Paced Auditory Serial Addition Test. Of these, 40 participants who exhibited confirmed fatigue based on flicker values were randomly assigned to either an exercise group (20&#xa0;min of aerobic exercise) or a rest group (20&#xa0;min of bed rest); n = 20 per group. Flicker values and electroencephalographic (EEG) parameters (mean power of theta, alpha, and beta waves) were measured before and after the intervention. Fatigue recovery was assessed through within-group comparisons of pre- and post-intervention values and between-group comparisons of change scores. In the exercise group, flicker values significantly increased post-intervention, and this change was significantly greater than that in the rest group. EEG analysis revealed a significant increase in theta power post-intervention in the exercise group. Additionally, alpha and beta power increased significantly, with changes greater than those in the rest group. Conversely, no significant changes in flicker values or EEG measures were observed in the rest group. Correlation analysis revealed that the degree of recovery in flicker values was significantly and positively correlated with increases in alpha and beta wave power. Aerobic exercise produced a significantly greater restorative effect on mental fatigue than bed rest, as evidenced by objective indicators such as flicker values and EEG measures. The findings suggest that aerobic exercise is a promising intervention for addressing mental fatigue in contemporary society.</p><p><?qj left?><?noindent??><i>Trial registration</i> UMIN000057499, Registered 3 April 2025 (retrospectively registered).</p>