Aims Social isolation in people living with schizophrenia is associated with poor quality of life and increased symptom severity. Volunteer befriending interventions are a potential strategy for addressing social isolation, but evidence of their effectiveness is limited, particularly in low- and middle-income countries. We assessed the experiences of volunteer befriending and tested its effectiveness for improving the quality of life of patients with schizophrenia in Bosnia and Herzegovina. Methods Between March 2018 and July 2020, we conducted a parallel-group, randomised controlled trial in adults with schizophrenia and poor quality of life at an outpatient clinic in Sarajevo. Patients were randomised to either the intervention, in which they were matched with a volunteer befriender with whom they met fortnightly over the 6-month intervention period, or treatment as usual. The primary outcome was quality of life measured on the Manchester Short Assessment and secondary outcomes were psychiatric symptoms and objective social outcomes. Outcome measurement was conducted by blinded researchers at 6- and 12-months. Results In total, 65 patients were randomised into the intervention (n = 33) and control arms (n = 32) and 55 (85%) completed follow-up assessments at 6 months. Patients in the intervention showed a significantly more favourable quality of life at 6 months (primary outcome; mean difference: 0.7, 95% CI [0.3–1.1], p = 0.003) and 12 months (mean difference: 1.7, 95% CI [1.1–2.3], p < 0.001). They also had significantly lower symptom levels at both follow-ups, and a significantly more favourable objective social situation after 12 months. Participants reported largely positive experiences. Conclusion The exploratory trial conducted at one site found sustained improvements in quality of life and reductions in psychiatric symptoms. This suggests that volunteer befriending may be a feasible and effective treatment for patients with schizophrenia in resource-limited contexts, such as Bosnia and Herzegovina.