Background: The regimens approved for the treatment of advanced head and neck squamous cell carcinoma (HNSCC) are accessible to only 1-3% of patients in low and middle-income countries due to cost. In our previous study, metronomic chemotherapy (MC) improved survival in this setting. Retrospective data suggest that a low dose of nivolumab may be efficacious. Hence, we aimed to assess whether the addition of low dose nivolumab to MC improved the overall survival. Methods: This was a randomised phase 3 superiority open-label study. Adult patients with relapsed -recurrent or newly diagnosed advanced HNSCC being treated with palliative intent with ECOG PS 0-1 were eligible. Patients were randomised 1:1 to MC consisting of methotrexate 15 mg/m2 PO weekly, celecoxib 200 mg PO daily and erlotinib 150 mg PO daily, or MC with intravenous nivolumab 20 mg flat dose once-every-3-weeks. Therapy was continued until disease progression or intolerable adverse events. Response assessment (RECIST version 1.1) was performed every 2 months. The primary endpoint was 1-year overall survival (OS) and this was a pre-specified interim analysis with the nominal p-value for efficacy being 0.006. Results: 151 patients were randomised, 75 in MC and 76 in the MC-I arm respectively. The addition of low dose nivolumab led to an improvement in the 1-year overall survival from 16.3% (95%CI 7.95-27.4) to 43.4% (95% CI 30.8-52.3) [Hazard ratio-0.545; 95%CI 0.362-0.82; P=0.00358]. The median overall survival in MC and MC-I arms was 6.7 months (95%CI 5.83 -8.07) and 10.1 months (95%CI 7.37-12.63) respectively (P=0.0052). The median progression-free survival in MC and MC-I arms was 4.57 months (95%CI 4.2 -5.3) and 6.57 months (95%CI 4.43-8.9) respectively (P=0.0021). Response rate in MC and MC-I arm were 49.3% (95% CI 37.8-60.8) and 65.2% (95%CI 53.4-75.4) respectively (P=0.085). The rate of grade 3 and above adverse events was 50% and 46.1% in MC and MC-I arm respectively (P=0.744). Conclusions: In this first-ever randomised study, the addition of low dose nivolumab led to improved overall survival and is an alternative standard of care for those who cannot access full dose nivolumab. Clinical trial information: CTRI/2020/11/028953.