This meta-analysis explores whether self-regulation in childhood relates to concurrent and subsequent levels of achievement, interpersonal behaviors, mental health, and healthy living. A comprehensive literature search identified 150 studies that met inclusion criteria (745 effect sizes; total n = 215,212). Data were analyzed using inverse-variance weighted random effects meta-analysis. Mean effect sizes from 55 meta-analyses provided evidence that self-regulation relates to 25 discrete outcomes. Results showed that self-regulation in preschool (∼age 4) was positively associated with social competency, school engagement, and academic performance, and negatively associated with internalizing problems, peer victimization, and externalizing problems, in early school years (∼age 8). Self-regulation in early school years was positively related to academic achievement (math and literacy), and negatively related to externalizing problems (aggressive and criminal behavior), depressive symptoms, obesity, cigarette smoking and illicit drug use, in later school years (∼age 13). Results also showed that self-regulation in early school years was negatively related to unemployment, aggressive and criminal behavior, depression and anxiety, obesity, cigarette smoking, alcohol and substance abuse, and symptoms of physical illness in adulthood (∼age 38). Random effects metaregression identified self-regulation measurement as the most important moderator of pooled mean effects, with task-based assessments and teacher-report assessments often showing stronger associations than parent-report assessments. Overall, findings from this meta-analysis provide evidence that self-regulation in childhood can predict achievement, interpersonal behaviors, mental health, and healthy living in later life.