Previous studies have demonstrated that the combination of high preoperative fibrinogen levels and high neutrophil-to-lymphocyte ratio (NLR) is associated with poor outcomes in various types of cancer. The present study assessed the prognostic value of a scoring system based on the combination of fibrinogen concentration and neutrophil-to-lymphocyte ratio (F-NLR) in untreated patients with resectable breast cancer (BC). The present study retrospectively analyzed 906 patients who received surgery for resectable BC. Univariate and multivariate analyses were performed to explore the association between the F-NLR score and survival status. The cut-off values for fibrinogen and NLR determined via receiver operating characteristic curve analysis were 3.21 g/l and 2.20, respectively. On the basis of these cut-off values, the whole cohort was divided into three groups according to their F-NLR score: Score 2, fibrinogen ≥3.21 g/l and NLR ≥2.20; score 1, fibrinogen ≥3.21 g/l or NLR ≥2.20; and score 0, fibrinogen <3.21 g/l and NLR <2.20. The F-NLR score was significantly associated with age (≤50 years vs. >50 years; P<0.001), tumor size (≤2 cm vs. >2 cm; P=0.001), lymph node status (P=0.029), TNM stage (I vs. II vs. III; P=0.002) and lymphovascular invasion (P<0.001). The 5-year disease-free survival (DFS) rates in the patients with F-NLR scores of 0, 1 and 2 were 95.7, 87.5 and 74.0%, respectively (P<0.001), and the 5-year overall survival (OS) rates were 97.8, 90.9 and 79.9%, respectively (P<0.001). Furthermore, multivariate analysis demonstrated that the F-NLR score independently predicted DFS [hazard ratio (HR), 2.279; 95% CI, 1.758–2.954; P<0.001] and OS (HR, 2.414; 95% CI, 1.738–3.353; P<0.001). In conclusion, the preoperative F-NLR score was an independent prognostic indicator for untreated patients with resectable BC.