Background: Stigmatisation is a source of chronic stress and a major barrier to recovery for people with mental illnesses. The internalisation of stigma can have a negative impact on an individual’s social relations and lead to feelings of loneliness and depression.

Aim: This research is aimed at testing the hypothesis that the internalised stigma of mental illness contributes to the intensification of depressive symptoms indirectly, through its impact on feelings of loneliness.

Methods: A total of 110 individuals with diagnoses of psychotic disorders (International Classification of Diseases–10th Revision (ICD-10): F20–F29) were assessed with measures of internalised stigma, loneliness, depression, positive and negative symptoms and global functioning. The ordinary least squares regression was used for data analysis.

Results: After adding loneliness to the regression model, the initially significant impact of internalised stigma on depressive symptoms disappeared. As expected, loneliness proved to be a full mediator in the relationship between stigma and depression.

Conclusion: The study findings provide useful insights into the mechanisms of the harmful effects of stigma on people with mental illness. Internalised stigma and loneliness should be considered important targets for interventions aiming to promote recovery.