Abstract Background A meta-analysis was conducted to investigate the much-debated relationship between the gene expression of programmed cell death-ligand 1 (PD-L1) and cancer patient prognosis. The prognostic value of measuring PD-L1 expression in non-small cell lung cancer (NSCLC) patients was analyzed. Methods We searched PubMed for studies about the relationship between PD-L1 expression and NSCLC patient prognosis. Only studies with patient survival data related to PD-L1 expression in NSCLC patients with different characteristics were included. The effect size (ES) for this analysis was the hazard ratio (HR) with 95% confidence intervals (CI) for overall survival (OS). Results Six studies with 1157 patients were included with the defined including and excluding criteria. There is no significant heterogeneity among the studies (I2  = 0%, p  = 0.683). PD-L1 expression was significantly associated with the differentiation of tumor (poor vs. well: OR = 1.91, 95% CI: 1.33–2.75, p  = 0.001). High PD-L1 expression was also correlated with poor prognosis in terms of the OS of patients with NSCLC (pooled HR = 1.75, 95% CI: 140–2.20, p  < 0.001; heterogeneity test: I2  = 0%, p  = 0.643). Conclusions NSCLC patients with positive PD-L1 expression exhibited poor OS. The PD-L1 expression was higher in tumors with poor differentiation.