A transdiagnostic continuum model of psychopathology predicts that ontological insecurity (the propensity toward self-fragmentation) will mediate the relationship between ideal self-discrepancy (perceived discrepancy between actual and ideal self) and depression, anxiety, and subclinical psychotic-like experiences (PLEs). A community sample of 142 participants completed a modified version of the Self-Discrepancy Scale (S-DS), the Ontological Insecurity Scale (OIS-34), the Depression and Anxiety subscales of the DASS-21, and the Positive subscale of the Community Assessment of Psychic Experiences (CAPE-P15). Hierarchical multiple regression analyses demonstrated that the distress arising from the ideal self-discrepancy significantly and positively predicted depression, anxiety, and PLEs. These relationships ceased to be significant once ontological insecurity entered the regression equation in the final step. In line with the transdiagnostic continuum model, ontological insecurity fully mediated the relationship between ideal self-discrepancy distress and all measures of psychopathology. The findings suggest that future research and psychological interventions might profit more by focusing on the distress arising from self-discrepancy and ontological insecurity than on self-discrepancy itself.