INTRODUCTION: Sugemalimab is the first China-developed programmed death-ligand 1 inhibitor that has proved to be effective as a first-line treatment for both metastatic squamous and non-squamous non-small cell lung cancer (NSCLC) when used in combination with chemotherapy. This study compared the cost-effectiveness of sugemalimab plus chemotherapy (sugema + chemo) with placebo plus chemotherapy (placebo + chemo) among metastatic squamous and nonsquamous NSCLC, respectively. METHODS: Separate Markov models were constructed to generate the cumulative healthcare costs and quality-adjusted life-years (QALYs) associated with two treatment strategies over a 20-year time horizon. Transition probabilities were estimated using survival data reported in the GEMSTONE-302 trial. Health state utilities and costs were derived from published literature, national databases, and local general hospitals. Sensitivity analyses were performed to test the robustness of our conclusions. RESULTS: Compared with first-line placebo + chem, sugema + chemo achieved an incremental cost-effectiveness ratio (ICER) of $57,842/QALY for patients with metastatic squamous NSCLC and achieved an ICER of $78,249/QALY for patients with metastatic non-squamous NSCLC. In our sensitivity analyses of a willingness-to-pay (WTP) threshold of $35,663 per QALY, the first-line sugema + chemo was only cost-effective for patient groups when the price of sugemalimab decreased. CONCLUSION: Sugema + chemo was not cost-effective as a first-line treatment for either metastatic squamous or metastatic nonsquamous NSCLC in Chinese patients compared with placebo + chemo. However, we found that sugema + chemo would be cost-effective in patients with metastatic squamous and non-squamous NSCLC when sugemalimab's price was decreased by > 39.0% and 64.8%, respectively.