Objectives The recommended treatment for limited‐stage small‐cell lung cancer (LS‐SCLC) is a combination of thoracic radiotherapy (TRT) and etoposide plus cisplatin (EP) chemotherapy, typically administered over 4–6 cycles. Nonetheless, the optimal duration of chemotherapy is still not determined. This study aimed to compare the outcomes of patients with LS‐SCLC who received either 6 cycles or 4–5 cycles of EP chemotherapy combined with TRT. Materials and Methods In this retrospective analysis, we utilized data from our prior prospective trial to analyze the outcomes of 265 LS‐SCLC patients who received 4–6 courses of EP combined with concurrent accelerated hyperfractionated TRT between 2002 and 2017. Patients were categorized into two groups depending on their number of chemotherapy cycles: 6 or 4–5 cycles. To assess overall survival (OS) and progression‐free survival (PFS), we employed the Kaplan–Meier method after conducting propensity score matching (PSM). Results Among the 265 LS‐SCLC patients, 60 (22.6%) received 6 cycles of EP chemotherapy, while 205 (77.4%) underwent 4–5 cycles. Following PSM (53 patients for each group), the patients in the 6 cycles group exhibited a significant improvement in OS and PFS in comparison to those in the 4–5 cycles group median OS: 29.8 months (95% confidence interval CI, 23.6–53.1 months) vs. 22.7 months (95% CI, 20.8–29.1 months), respectively, p = 0.019; median PFS: 17.9 months (95% CI, 13.7–30.5 months) vs. 12.0 months (95% CI, 9.8–14.2 months), respectively, p = 0.006. The two‐year and five‐year OS rates were 60.38% and 29.87% in the 6 cycles group, whereas 47.17% and 15.72% in the 4–5 cycles group, respectively. Conclusion Patients diagnosed with LS‐SCLC who were treated with EP regimen chemotherapy combined with TRT exhibited notably enhanced survival when administered 6 cycles of chemotherapy, as compared to those who underwent only 4–5 cycles.