Few studies have explored meaning in life as a mediator between adverse childhood experiences (ACEs) and mental health. This study examined the protective and risk factors associated with meaning in life, as they mediate the effect of ACEs on mental health. The sample was 293 university students in Hong Kong (mean age = 21 years). The results of analyses based on three-wave longitudinal data and structural equation modeling demonstrated that the presence of meaning mediated the negative association between ACEs and happiness, and that meaning confusion mediated the positive association between ACEs and depression and anxiety. This study provides evidence that the presence of meaning may play a protective role and that meaning confusion may be a risk factor for the effects of ACEs on mental health. This study's results have implications for the development of prevention and intervention strategies to alleviate the detrimental impact of ACEs and promote mental health in young adults.