Background: This study aims to determine the relationship between preoperative plasma fibrinogen levels and the prognosis of patients with nonmetastatic renal cell carcinoma (RCC), including overall survival (OS), cancer-specific survival (CSS) and progression-free survival (PFS). Methods: We retrospectively analysed the clinical data and prognostic information of 1194 nonmetastatic RCC patients who received radical nephrectomy or nephron-sparing surgery between 2005 and 2015 at our institution. Serum was collected for fibrinogen detection in the week prior to curative operation, and prognostic information was regularly collected by specially trained personnel. The cutoff value of the preoperative plasma fibrinogen level was defined by receiver operating characteristic (ROC) analysis. The chi-square test was used to analyse the association between preoperative fibrinogen level and clinical characteristics. Kaplan-Meier analysis was used to calculate survival curves, and significant differences were determined by the log-rank test. Other significant prognostic factors were evaluated by the Cox multivariate proportional hazard model. Results: The median follow-up period after radical or partial nephrectomy was 42.4 months (ranging from 0.433 to 146.37 months). The optimal preoperative plasma fibrinogen concentration was 3.975 g/L. The preoperative fibrinogen level was significantly associated with age, pathological T stage, sarcomatoid differentiation, necrosis and vein tumour thrombus (all p<0.05). High plasma fibrinogen levels were related to poor prognosis in terms of OS (p<0.001), CSS (p<0.001) and PFS (p<0.001). Multivariate analysis showed that the preoperative fibrinogen level remained an independent prognostic factor for OS (HR: 3.22, 95%CI: 1.87-5.55, p<0.001), CSS (HR: 4.12, 95%: 2.15-7.89, p<0.001) and PFS (HR: 3.137, 95%CI: 2.17-4.53, p<0.001). Conclusions: High preoperative plasma fibrinogen level is an independent negative prognostic factor for OS, CSS and PFS in patients with non-metastatic RCC. Preoperative plasma fibrinogen could be an ideal indicator for evaluating the outcomes of postoperative patients with nonmetastatic RCC.