The aimed to evaluate the effects of low and moderate-intensity aerobic exercise on psychological well-being (PWB) and quality of life (QoL) among older people. Fortyfive male Iranian adults aged 65–80 years were selected according to the eligibility criteria and randomly assigned to a low-intensity group (LIG) (40–50% of maximum heart rate), moderate-intensity group (MIG) (60–70% of maximum heart rate) and control group (CG). The exercise protocols consisted of 12 weeks of aerobic exercise (two sessions per week). Psychological well-being and QoL were assessed through the Ryff’s Psychological Well-being Scale and the World Health Organization QoL Questionnaire. The statistical analysis for psychological well-being indicated that a significant main group (between-group) (F = 11.777, p < 0.001, ηp2 = 0.359), time (within-group) (F = 58.983, p < 0.001, ηp2 = 0.584) and interaction effect (group × time) (F = 20.146, p < 0.001, ηp2 = 0.490) for PWB total score. Bonferroni post-hoc tests revealed that the PWB total score in the MIG group was more significant than both LIG (p = 0.003) and CG (p < 0.001). Results for PWB components including self-acceptance, positive relationships with others, autonomy, purposeful life, and environmental mastery revealed no significant differences (p > 0.05). While there was a significant difference between the groups for personal growth component. Bonferroni post-hoc tests revealed that the personal growth in the MIG group was more significant than both LIG (p = 0.028) and CG (p < 0.001). Result for QoL indicated significant differences for the main group (F = 13.277, p < 0.001, ηp2 = 0.387), time (F = 25.533, p < 0.001, ηp2 = 0.378) and interaction effect (F = 9.992, p < 0.001, ηp2 = 0.332) for QoL total scale. Bonferroni post-hoc tests revealed that the QoL total scale in the MIG group was more significant than both LIG (p = 0.003) and CG (p < 0.001)components including Physical health, Social relationships, Health environment revealed no signi
