Treatment of non-small-cell lung cancer depends heavily on the cancer stage, and immunotherapy can play a major role at any stage. For locally advanced stages, the addition of an immune checkpoint inhibitor (ICI) to neoadjuvant chemotherapy improves pathological response and event-free survival. In the adjuvant setting, adding ICI, after adjuvant chemotherapy for resectable cancer, increases the disease-free survival. In unresectable stage III treated with concomitant chemotherapy and radiotherapy, adding ICI as a maintenance therapy increases progression-free survival and overall survival. In the metastatic setting, the addition of ICI to chemotherapy improves overall survival, progression-free survival, and response rates irrespective of the PD-L1 expression. ICI on its own may be considered in cases of PD-L1 expression equal or greater than at least 50%.