BACKGROUND: The advent of immunotherapies has ushered in a new era in the treatment of non-small cell lung carcinoma. Although immunotherapies are associated with improved clinical outcomes, studies report a median overall survival of 11 months with progression-free survival of 2.5 months with the use of nivolumab for pretreated metastatic non-small cell lung cancer. Herein, we describe a case of advanced non-small cell lung carcinoma that has shown exceptional response to immunotherapy, with the patient being in complete response for the past 6 years since commencement of nivolumab. CASE PRESENTATION: We report the case of a 58-year-old female Caucasian, an ex-smoker with 40-pack-year history of smoking, who presented with cough and chest pain and was subsequently diagnosed with metastatic pulmonary adenocarcinoma. The tumor was positive for Kirsten rat sarcoma virus oncogene KRAS-G12C mutation and had high programmed death-1 ligand expression. She was commenced on first-line chemotherapy with carboplatin and gemcitabine with disease response, then continued on maintenance pemetrexed. She was then commenced on immunotherapy with nivolumab, with complete response for a total of 6 years. She does not report any adverse events. Currently, she shows no evidence of recurrence of non-small cell lung carcinoma. CONCLUSION: The exceptional response to immunotherapy seen in this case may be explained by the presence of Kirsten rat sarcoma virus oncogene mutation, which is associated with enhanced clinical response to programmed death-1 ligand inhibitors. This report emphasizes the urgent need for further studies evaluating the role of Kirsten rat sarcoma virus oncogene mutation in determining the clinical efficacy of immunotherapies. This would enable us to make effective evidence-based clinical interventions in the treatment of non-small cell lung carcinoma.