Introduction and Aims: Retrospective studies have shown a strong association between experiencing maltreatment in childhood and subsequent illicit substance or alcohol use. Prospective studies are rarer, with limited data following subjects into adulthood. We report findings from a prospective record-linkage analysis, which examines whether notified and/or substantiated child maltreatment is associated with substance (SUD) or alcohol use disorders (AUD) in early adulthood when participants are 30 years old. Design and Methods: We linked data from a statutory child protection agency of prospectively notified and substantiated child maltreatment to a survey of a birth cohort recruited from the main maternity hospital of Brisbane. The main outcomes were 30-day and lifetime diagnoses of SUD or AUD at 30-year follow-up as measured by the Composite International Diagnostic Interview, Auto version. Results: Of the 2861 people at the 30-year follow-up, 103 (3.6%) had a history of agency-substantiated maltreatment by 16 years. On adjusted analyses, AUD in the previous 30 days or lifetime SUD were both significantly associated with childhood maltreatment. Of maltreatment subtypes, 30-day AUD at 30 years of age was particularly associated with physical and emotional abuse while SUD was associated with sexual maltreatment. Recurring or multiple forms of abuse had the worst outcomes. Discussion and Conclusions: Child maltreatment, especially involving physical and sexual abuse, predicts AUD and SUD that extends to people in their 30s. Children with more than one type of maltreatment are at particular risk. Further research may help to identify possible predictors of long-term outcomes of child maltreatment.