Lung cancer is worldwide the most common malignancy. Standard of care treatments for early-stage non-small-cell lung cancer (NSCLC) include surgery and adjuvant chemotherapy. However, these patients continue to have poor prognosis due to systemic or local relapse. Immunotherapy has been considered as a novel approach to improve survival in patients with early-stage NSCLC. Since immune checkpoint inhibitors have transformed the treatment of advanced NSCLC, there is a growing interest in the role of immunotherapy in early-stage NSCLC. In this review, we summarize reported and ongoing clinical trials of immunotherapy in both neoadjuvant and adjuvant settings. We also highlight unaddressed issues in this field of research, such as the predictive markers, the optimal combination therapy, and the need for adjuvant immunotherapy. More studies are needed to optimize the treatment regimen of immunotherapy in patients with early-stage NSCLC.