Background: South Korean youth’s strong emphasis on fairness and meritocracy, intensified during COVID-19, may have heightened exposure to morally injurious experiences arising from conflicts between personal values and societal constraints.

Objective: This study investigated the longitudinal associations between morally injurious events (MIEs) and mental health, and examined the mediating roles of self-compassion components among South Korean youth.

Methods: At Time 1, a total of 1,567 young adults aged 20–29 completed the Korean versions of the Moral Injury Events Scale, the Self-Compassion Scale, and the General Mental Health Questionnaire, along with demographic information. After nine months, 726 participants completed a follow-up online survey. Parallel mediation models with 10,000 bootstrap resamples were conducted to test whether six self-compassion subscales mediated the relationships between two types of MIEs—perceived transgressions and perceived betrayals—and general mental health at Time 2.

Results: Both perceived transgressions and perceived betrayals were significantly associated with all six self-compassion components, including positive (e.g., self-kindness, mindfulness, and common humanity) and negative (e.g., self-judgment, isolation, and over-identification) factors. Among these, self-judgment and isolation accounted for significant indirect associations between MIEs and poorer mental health, whereas the positive components did not show significant indirect effects.

Conclusion: Moral injury is associated with enduring adverse mental health outcomes among youth. The findings highlight that negative self-compassion components—particularly self judgment and isolation—appear to represent key psychological pathways associated with moral distress and mental health outcomes. Interventions that cultivate self-compassion while reducing self-criticism and feelings of isolation may help mitigate the long-term psychological impact of moral injury among young people.