Previous studies showed albumin at diagnosis could be used to predict outcome in patients with diffuse large B-cell lymphoma (DLBCL), but whether albumin could improve the international prognostic index (IPI) risk stratification remains unknown. Herein, we retrospectively analyzed 440 de novo DLBCL patients in this study. The cutoff value of albumin was 39.2 g/L. Patients with high serum albumin showed superior OS and PFS (p = 0.002 and p < 0.001, respectively). According to IPI, there were 163 patients (37.0%) in low-risk group, 107 (24.3%) in low-intermediate risk group, 114 (25.9%) in high-intermediate risk group and 56 (12.7%) in high-risk group. Further analysis showed high albumin could identify a subgroup of patients with extremely superior OS and PFS in low IPI risk patients (p = 0.022 and p = 0.034, respectively). Multivariate analysis revealed that high albumin was an independent prognostic factor for OS (relative ratio [RR] 0.122; 95% confidence interval [CI] 0.021-0.715, p = 0.020) and trend for PFS (RR 0.417; 95% CI 0.168-1.035, p = 0.059). In conclusion, our study suggests that albumin at diagnosis is a simple and effective prognostic factor in DLBCL patients, allowing the identification of a superior outcome subgroup in low-risk patients, which may help to guide treatment in clinical trial.