Background This present study aimed to investigate the prognostic significance of the Advanced Lung Cancer Inflammation Index (ALI) in peripheral blood of limited disease small-cell lung cancer (LD-SCLC) treated with chemoradiotherapy. Methods We included 87 consecutive LD-SCLC patients treated from 2005 to 2019 in South Korea. All patients were treated with definite chemoradiotherapy. Chemotherapy was etoposide combined with either carboplatin or cisplatin given mainly concomitantly with radiotherapy. ALI was calculated as the formula: body mass index x serum albumin/neutrophil-lymphocyte ratio (NLR). Survival curves were generated using the Kaplan-Meier method. Cox proportional hazards regression analyses were used to estimate hazard ratios (HRs) and determine risk factors predicting mortality. Results We classified 38 patients as high ALI (ALI ≥ 44.3) and 48 as low ALI group (ALI < 44.3). Compared with the low ALI group, patients in the high ALI group had a longer overall survival (OS) time. On multivariate analysis, performance status (P = 0.0222), prophylactic cranial irradiation (P = 0.0007), and ALI (P = 0.0044) were all independent prognostic factors for OS. Conclusions The Results of this study demonstrated that high ALI was significantly associated with better OS in LD-SCLC patients treated with chemoradiotherapy. For the initial evaluation of patients with LD-SCLC, pre-treatment ALI could predict the patients with good prognosis and be a useful prognostic marker in clinical practice.