Objectives: Childhood trauma is a common risk factor for adult psychiatric disorders, such as schizophrenia (SZ) and bipolar-I disorder (BD). However, its association with schizotypal personality traits, as well as cognitive and social cognitive abilities, is less well studied in these populations. Methods: In a cohort of 79 SZ cases, 84 BD cases, and 75 healthy controls (HCs), clinically significant levels of childhood trauma exposure (according to scores on the Childhood Trauma Questionnaire; CTQ) were evident in 54 SZ, 55 BD, and 26 HC individuals. Trauma-exposed and non-exposed groups were compared on schizotypal personality features (schizotypy) measured with the Schizotypal Personality Questionnaire (SPQ). Cognitive assessments included executive function, working memory, attention, and immediate and delayed memory. Social cognitive measures assessed facial emotion processing and theory-of-mind abilities. Results: Trauma-exposed participants showed higher levels of schizotypy, especially suspiciousness, relative to non-exposed individuals, regardless of clinical or HC status. Furthermore, trauma-exposed individuals showed deficits specifically in social cognitive, but not general cognitive abilities, regardless of clinical or HC status. These trauma-related results were found in the context of higher schizotypy levels in both SZ and BD relative to HC, and lower cognitive and social cognitive performance in SZ, relative to BD and HC groups. Conclusions: These findings suggest that childhood trauma exposure impacts long-term schizotypy outcomes, especially paranoid ideation (suspiciousness), as well as complex social cognitive abilities in both healthy and psychotic populations. However, cognitive deficits associated with psychotic illness may not be distinguishable from those related to trauma exposure in previous studies. Practitioner points: Findings. Childhood trauma exposure is associated with increased schizotypal features (in particular paranoid ideation) and complex social cognitive abilities, independently of the diagnosis of psychotic disorder. Cognitive and social cognitive deficits were larger in schizophrenia compared to bipolar-I cases and healthy controls, but increased schizotypal features were observed in both schizophrenia and bipolar-I disorder relative to healthy controls. Limitations. We were unable to distinguish the specific effects of particular childhood trauma exposures due to the high rate of exposure to more than one type of maltreatment. Retrospective assessment of childhood trauma in adulthood cannot be externally validated, and associations with behavioural traits in later life may be confounded by other factors not studied here.