Adverse childhood experiences (ACEs) are widely associated with mental health disorders, such as depression, post-traumatic stress disorder (PTSD), and suicidality. Resilience plays a role in mediation and moderation of these associations, yet there is limited data from Kenya on this. This cross-sectional study examined the role of resilience in the relationship between ACEs and mental health outcomes among 1,972 participants aged 14–25 years in the Nairobi Metropolitan area. Participants completed the Trauma and Distress Scale (ACEs), Patient Health Questionnaire-9 (depression), Columbia-Suicide Severity Rating Scale (suicidality), Harvard Trauma Questionnaire (PTSD), and Adult Resilience Measure-Revised (resilience). Analyses of moderation and mediation using Hayes Process Macro indicated that resilience moderated the association between ACEs with PTSD and depression, with minimal effect on suicidality. It also moderated specific associations, including emotional/physical neglect on ideation, physical abuse on lifetime behavior (p = 0.0479), and total ACEs on recent behavior (p = 0.0514). Resilience also partially mediated the effects of ACEs on PTSD and depression, and fully mediated suicidality for specific ACE domains (emotional neglect, physical neglect, and physical abuse on suicidal ideation and all ACEs on recent suicidal behaviors). Building resilience mitigates the effects of ACEs on depression, PTSD, and suicidality among Kenyan youth.