The reduction in lung cancer mortality rates over the past decade can be partially ascribed to advancements in immunotherapy. Immune checkpoint inhibitors (ICIs) have transformed the therapeutic landscape for advanced non-small cell lung cancer (NSCLC) and have recently been evaluated in multiple clinical trials to confirm their safety and efficacy in the neoadjuvant, adjuvant and perioperative settings for patients with resectable NSCLC. The Food and Drug Administration (FDA) has granted approval for adjuvant atezolizumab following platinum-doublet chemotherapy, neoadjuvant nivolumab and platinum-doublet chemotherapy, adjuvant pembrolizumab after platinum-doublet chemotherapy, and neoadjuvant/adjuvant pembrolizumab for resectable NSCLC, with potential forthcoming approvals for additional agents or indications. Novel data, approvals, and emerging research findings are dramatically shifting the accepted standards of care over just a few years. Despite these advances, the optimal application of these treatments is not entirely straightforward. This article summarizes the biological rationale for immunotherapy and the important clinical trials regarding perioperative ICIs. We also further outline the controversies and future directions to better guide the individualized treatment of NSCLC patients.