Based on the results of the CheckMate 017 and CheckMate 057 studies, nivolumab therapy has become a new standard treatment for both squamous and non-squamous non-small-cell lung cancer (NSCLC). However, due to the specific inclusion criteria of these clinical trials, the efficacy and safety of nivolumab in real-world practice were not certain. In general, the real-world results of nivolumab treatment have been consistent with those obtained in clinical trials. Additional analyses of the real-world data have made the identification of prognostic factors possible. Good performance status is the most significant predictor of clinical benefit. Brain metastases, liver metastases, EGFR mutation, malignant pleural effusion, and a high number of metastatic sites were identified as negative prognostic factors. By contrast, a longer time to disease progression (>6 months) from the beginning of prior chemotherapy and an objective response to chemotherapy seem to have positive prognostic value in the case of nivolumab treatment. In terms of patient age, the data are inconclusive. Some blood biomarkers can also be considered significant prognostic factors.