Background: The ongoing worldwide epidemic of Coronavirus Disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has posed a huge threat to global public health. However, with regard to the effects of inflammatory markers on the severity of COVID-19, studies have reported associations that vary in strength and direction. Aims: In the meta-analysis, we aimed to provide an overview of the association of inflammatory markers with severity of COVID-19. Methods: The following databases were searched: PubMed, Embase, Cochrane Library, Wanfang database and CNKI (China National Knowledge Infrastructure) database until March 20, 2020. Weighted mean difference (WMD) and 95% confidence intervals (CIs) were pooled using random or fixed-effects models. Results: A total of 16 studies were included in our analysis comprising of 3962 patients with COVID-19. Random-effects results demonstrated that patients with COVID-19 in non-severe group had lower levels for CRP (WMD = -41.78 mg/l, 95% CI = [-52.43, -31.13], P < 0.001), PCT (WMD = -0.13 ng/ml, 95% CI = [-0.20, -0.05], P < 0.001), IL-6 (WMD = -21.32 ng/l, 95% CI = [-28.34, -14.31], P < 0.001), ESR (WMD = -8.40 mm/h, 95% CI = [-14.32, -2.48], P = 0.005), SAA (WMD = -43.35 μg/ml, 95% CI = [-80.85, -5.85], P = 0.020) and serum ferritin (WMD = -398.80 mg/l, 95% CI = [-625.89, -171.71], P < 0.001), compared with those in severe group. Moreover, survivors had lower level for IL-6 than non-survivors with COVID-19 (WMD = -4.80 ng/ml, 95% CI = [-5.87, -3.73], P < 0.001). These results were consistent through sensitivity analysis and publication bias assessment. Conclusions: The meta-analysis highlights the association of inflammatory markers with the severity of COVID-19. Measurement of inflammatory markers might help clinicians to monitor and evaluate the severity and prognosis of COVID-19.