Three hundred and twenty-seven patients ≥60 years old and diagnosed with osteoarthritis (OA) and insomnia were randomized to undergo 8 weeks of telephone-delivered cognitive behavioural therapy for insomnia (CBT-I; n=163) or education only (n=164). The primary outcome of interest was severity of insomnia measured on the Insomnia Severity Index (ISI) at 2 months and 12 months follow-up. Secondary outcomes of interest included arthritis pain and interference with activities using the Brief Pain Inventory short form (BPI-sf), depression using the Patient Health Questionnaire (PHQ-8), and fatigue was measured on the Flinders Fatigue Scale (FFS). Moreover, incidence of adverse and serious adverse events were recorded. The rate of adherence of interventions was 80% and 89.6% in the CBT-I and control groups, respectively. Insomnia severity index scores and fatigue severity scores were significantly reduced in the CBT-I group vs control at both timepoints (p<0.05 for all). Depression scores on the PHQ, BPI-sf activity interference, and BPI-sf pain severity scores were significantly in favour of the CBT-I group vs control at 2 months (p<0.05 for all) but not at 12 months follow-up (p>0.05 for both). In both groups, 27 serious adverse events were observed from baseline to 12 months follow-up, none of which were treatment-related.