Abstract Objective Cemiplimab, a novel PD-1 inhibitor, exhibits significant antitumor activity against advanced non-small cell lung cancer (NSCLC). However, the cost-effectiveness of this drug for the treatment remains unclear. This study aimed to assess the cost-effectiveness of cemiplimab plus chemotherapy compared to chemotherapy for the treatment of advanced NSCLC, from the perspective of the United States payer. Methods A partitioned survival approach was developed to project the disease progression of NSCLC. Overall survival (OS) and progression-free survival (PFS) data were obtained from the EMPOWER lung 3 trial and extrapolated to estimate long-term survival outcomes. Direct medical costs and utility data were collected. The primary outcome measure, the incremental cost-utility ratio (ICUR), was used to evaluate the cost-effectiveness of cemiplimab plus chemotherapy regimen. One-way sensitivity analyses (OWSA) and probabilistic sensitivity analyses (PSA) were conducted to assess the robustness of the results. Results In the base-case analysis, the ICUR for cemiplimab plus chemotherapy versus chemotherapy alone was estimated to be $395,593.8 per quality-adjusted life year (QALY). OWSA revealed that the results were sensitive to Hazard ratio value, utility of PFS, and cost of cemiplimab. PSA demonstrated that cemiplimab plus chemotherapy exhibited 0% probability of cost-effectiveness.In hypothetical scenario analysis, the ICUR of two regimens was $188.803.3/QALY. OWSA revealed that the results were sensitive to the discount rate, utility, and cost of cemiplimab. PSA indicated that cemiplimab plus chemotherapy achieved at least an 11.5% probability of cost-effectiveness. Conclusion Our cost-effectiveness analysis suggests that, at its current price, cemiplimab plus chemotherapy regimen is unlikely to be a cost-effective option compared with chemotherapy alone for advanced NSCLC patients, based on a threshold of $150,000 per QALY, from the perspective of the US payer.