This study aimed to assess functional disability and associated factors among people with severe mental illness attending public hospitals in Harar town, Eastern Ethiopia.

An institution-based cross-sectional study was conducted in public hospitals found in Harar town, Eastern Ethiopia, from 1 April to 10 May 2023.

A total of 342 patients with severe mental illness attending public hospitals in Harar town, Eastern Ethiopia, were included.

The main outcome of this study was functional disability, which was measured using a 12-item version of the WHO Disability Assessment Schedule.

In this study, the mean (±) score of functional disability among patients with severe mental illness was 31.8 (±9.6) (95% CI: 30.7 to 32.8). The multiple linear regression model revealed that unemployment (β: 1.93; 95% CI: 0.28 to 3.59), total illness duration (5–10 years and above 10 years) (β: 3.71; 95% CI: 1.95 to 5.48 and β: 4.51; 95% CI: 2.41 to 6.62, respectively), age at illness onset (β: –0.37; 95% CI: –0.45 to –0.28), having drug side effects (β: 3.05; 95% CI: 1.46 to 4.63), medication non-adherence (β: 6.15; 95% CI: 4.56 to 7.73) and having high perceived stigma (β: 2.27; 95% CI: 0.72 to 3.82) were significantly associated with functional disability.

Patients with severe mental illness had a high mean functional disability score. Unemployment, age at onset of mental illness, total duration of illness, medication side effects, medication non-adherence and higher perceived stigma were factors that were associated with functional disability. Given the mean functional disability score observed among respondents, a multipronged intervention strategy that prioritises early detection and management of severe mental illness, particularly targeting individuals at risk, is recommended to mitigate disability and enhance quality of life.