<p>Forgiveness has been evidenced to promote health-related quality of life (HRQoL); however, it is rarely known about why and under what conditions forgiveness affects older people’s HRQoL. This study pioneered the investigation into (1) the mediating role of trait anger in the relationship between forgiveness and older people’s HRQoL and (2) the moderating role of gender in these relationships. Participants were 308 adults aged between 60 and 98 years (<i>Mean</i>_age = 71.69 years, <i>SD</i> = 7.50) in Nanjing, China.a The results showed that trait anger mediated the positive effects of forgiveness on several dimensions of HRQoL, particularly mental health part. However, gender did not moderate any of the mediating relationships. The findings highlight the significance of forgiveness and regulation of trait anger in promoting older adults’ HRQoL, especially mental health. Moreover, there may be no need to consider gender differences when implementing relevant interventions, but future research should further verify gender differences in these mediating relationships in other contexts.</p>