The prognostic role of inflammation index like neutrophil‐to‐lymphocyte ratio (NLR) in colorectal cancer (CRC) remains controversial. We conduct a meta‐analysis to determine the predictable value of NLR in the clinical outcome of CRC patients. The analysis was carried out based on the data from 16 studies (19 cohorts) to evaluate the association between NLR and overall survival (OS) and progression‐free survival (PFS) in patients with CRC. In addition, the relationship between NLR and clinicopathological parameters was assessed. Hazard ratio (HR) or odds ratio (OR) with its 95% confidence interval (CI) was used as the effect size estimate. Our analysis results indicated that elevated pretreatment NLR predicted poorer OS (HR: 1.813, 95% CI: 1.499–2.193) and PFS (HR: 2.102, 95% CI: 1.554–2.843) in patients with CRC. Increased NLR is also significantly associated with the poorer differentiation of the tumor (OR: 1.574, 95% CI: 1.226–2.022) and higher carcino‐embryonie antigen (CEA) level (OR: 1.493, 95% CI: 1.308–1.705). By these results, we conclude that NLR gains a prognostic value for patients with CRC. NLR should be monitored in CRC patients for rational stratification of the patients and adjusting the treatment strategy. What's new? Although correlated with the severity of disease course, the impact of neutrophil‐to‐lymphocyte ratio (NLR) on survival and tumor characteristics in cancer patients remains unclear. In the meta‐analysis presented here, elevated pre‐treatment NLR was found to predict poor overall survival in patients with colorectal cancer. NLR was also associated with unfavorable biologic behavior in colorectal cancer. The findings suggest that NLR, as an inexpensive and widely available index, should be routinely monitored in colorectal cancer patients.