Background Assessment of personality functioning in different stages of psychotic disorders could provide valuable information on psychopathology, course of illness and treatment planning, but empirical data are sparse. Aims To investigate personality functioning and sense of self in individuals at ultra-high risk (UHR) for psychosis and with first-episode psychosis (FEP) in comparison with a clinical control group of individuals with borderline personality disorder (BPD) and healthy controls. Method In a cross-sectional design, we investigated personality functioning (Structured Interview of Personality Organization, STIPO; Level of Personality Functioning Scale, LPFS) and disturbances of the basic self (Examination of Anomalous Self-Experience, EASE) in 107 participants, comprising 24 individuals at UHR, 29 individuals with FEP, 27 individuals with BPD and 27 healthy controls. Results The UHR, FEP and BPD groups had moderate to severe deficits in personality organisation (STIPO) compared with the healthy control group. Self-functioning with its subdomain (facet) ‘self-direction’ (LPFS) was significantly worse in participants with manifest psychosis (FEP) compared with those at-risk for psychosis (UHR). The FEP group showed significantly worse overall personality functioning than the UHR group and significantly higher levels of self-disturbance (EASE) than the BPD group, with the UHR group lying between these diagnostic groups. Hierarchical cluster analysis based on the seven STIPO domains yielded three clusters differing in level of personality functioning and self-disturbances. Conclusions Our data demonstrate that psychotic disorders are associated with impaired personality functioning and self-disturbances. Assessment of personality functioning can inform treatment planning for patients at different stages of psychotic disorder.