Breast cancer (BC), obesity, and metabolic syndrome (MetS) shared a common mechanism of dysregulated metabolism and inflammatory response in disease initiation. Neutrophil-to-lymphocyte ratio (NLR) is associated with adverse survival of BC patients. The aim of this study is to identify risk effect between NLR and BC in Chinese population with or without obesity and MetS. BC and age-matched breast benign disease (BBD) patients were retrospectively analyzed from Comprehensive Breast Health Center, Shanghai Ruijin Hospital. MetS was defined using AHA/NHLBI criteria. Individuals were classified into very low (0-1.30), low (1.31-1.67), intermediate (1.68-2.20), and high (>2.20) NLR subsets by each NLR quartile. In all, 1540 BC and 1540 BBD patients were included. Univariate and multivariate analysis found that NLR (OR: 1.27, 95% CI: 1.16-1.39, P < .001) and obesity (OR: 1.19, 95% CI: 1.00-1.42, P = .046) but not MetS (P = .060) were significantly associated with increased BC risk. Intermediate or high NLR substantially increased BC risk compared to very low NLR group (OR: 1.57, 95% CI: 1.29-1.92, P < .001; OR: 1.84, 95% CI: 1.50-2.25, P < .001; respectively) in whole population. Subgroup analysis found that the impact of higher NLR on BC risk was more obvious in patients without obesity (intermediate NLR, OR: 1.72, 95% CI: 1.37-2.16, P < .001; high NLR, OR: 1.92, 95% CI: 1.53-2.41, P < .001) or without MetS (intermediate NLR, OR: 1.70, 95% CI: 1.35-2.14, P < .001; high NLR, OR: 1.98, 95% CI: 1.57-2.51, P < .001). Higher preoperative NLR was found in BC patients compared with BBD patients. Intermediate to high NLR level substantially increased BC risk, which was more relevant for those without obesity or MetS.