BACKGROUNDThe prognostic value of C-reactive protein (CRP) in patients with bladder cancer (BCa) has been widely analysed; however, the results remain conflicting. Therefore, we performed this meta-analysis to identify the precise role of CRP level in predicting BCa prognosis.METHODSPubMed, Web of Science, Embase and Cochrane Library databases were comprehensively searched until 19 April 2024. The impact of CRP level on predicting the prognosis of patients with BCa was examined using combined hazard ratios (HRs) and 95% confidence intervals (CIs). The relationship between CRP level and BCa clinicopathological characteristics was investigated by combining the odds ratios (ORs) with 95%CIs.RESULTSTwenty studies with 7276 patients were enrolled in this study. As revealed by pooled data, elevated CRP levels were markedly related to poor overall survival (OS) (HR = 2.02, 95%CI = 1.41-2.90, p < .001), inferior cancer-specific survival (CSS) (HR = 1.46, 95%CI = 1.29-1.66, p < .001), shortened recurrence-free survival (RFS) (HR = 1.25, 95%CI = 1.17-1.33, p < .001) and dismal progression-free survival (PFS) (HR = 2.28, 95%CI = 1.80-2.90, p < .001) in BCa patients. Nevertheless, there was no significant relationship between CRP level and sex, tumour size, tumour grade or lymph node metastasis (LNM) in BCa.CONCLUSIONSElevated CRP levels were significantly related to poor OS, CSS, RFS and PFS of BCa patients with BCa. CRP could act as a reliable biomarker for predicting the short- and long-term survival of patients with BCa in clinical practice.