BackgroundThe combination of immunotherapy and chemotherapy for extensive-stage small-cell lung cancer (ES-SCLC) was primarily carried out with a combination of immune checkpoint inhibitors (ICIs) and platinum-etoposide (EP). It is likely to be more effective in treating ES-SCLC than EP alone, but could result in high healthcare costs. The study aimed to investigate the cost-effectiveness of this combination therapy for ES-SCLC.MethodsWe searched literature from the following databases: PubMed, Embase, Cochrane Library, and Web of Science for studies on cost-effectiveness of immunotherapy combined with chemotherapy for ES-SCLC. The literature search period was up to April 20, 2023. The quality of the studies was evaluated using the Cochrane Collaboration's tool and Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist.ResultsA total of 16 eligible studies were included in the review. All studies met CHEERS recommendations, and all randomized controlled trials (RCTs) in these studies were rated as having low risk of bias using the Cochrane Collaboration's tool. The treatment regimens compared were ICIs plus EP or EP alone. All studies mainly used incremental quality-adjusted life year and incremental cost-effectiveness ratio as outcomes. Most ICIs plus EP treatment regimens were not cost-effective based on corresponding willingness-to-pay thresholds.ConclusionsAdebrelimab plus EP and serplulimab plus EP were probably cost-effective for ES-SCLC in China, and serplulimab plus EP was probably cost-effective for ES-SCLC in the U.S. Lowering the price of ICIs and selecting ES-SCLC patients who were sensitive to ICIs could improve the cost-effectiveness of the ICIs-combined treatment.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12913-023-09727-7.