Lung cancer is the leading cause of cancer-related mortality worldwide. Treatment with immunotherapy has made a significant impact on the outcomes for those patients suffering from lung cancer and its usage is currently an established treatment modality. Immune checkpoint inhibition that has blocking antibodies which target cytotoxic T-lymphocyte antigen-4 (CTLA-4) along with the programmed cell death protein 1 (PD-1) pathway [programmed death - 1/programmed death-ligand 1 (PD-L1)] have shown promising results for numerous malignancies. Nivolumab and pembrolizumab have been approved as PD-1 blocking antibodies while atezolizumab, avelumab, and durvalumab are approved as PD-L1 blocking antibodies by 'US Food and Drug Administration'. Immune checkpoint inhibitors have been found to statistically improve the survival of patients with lung cancer and have emerged as the primary immunotherapy in lung cancer and have changed the treatment paradigm for advanced disease. Despite such benefits, treatment with immune checkpoint inhibitors is associated with a unique pattern of immune-related adverse effects or side effects. Also, resistance is routinely developing in patients treated with immune checkpoint inhibitors. The current review provides an overview of immune checkpoint inhibitor treatment in lung cancer, its resistance, and adverse effects.