Objectives: To assess the value of positron emission tomography/computed tomography (PET/CT) in the efficacy evaluation of patients undergoing neoadjuvant immunotherapy plus chemotherapy, and to analyze its correlation with postoperative pathology. Methods: The PET/CT metabolic parameters and CT size were retrospectively analyzed before and after neoadjuvant immunotherapy plus chemotherapy in 67 patients with resectable stage II/IIIA non-small-cell lung cancer (NSCLC). CT assessment based on immune response evaluation criteria in solid tumor criteria ((i)RECIST) was compared with PET/CT assessment based on the response criteria in solid tumors (PERCIST). The correlations between PET/CT metabolic parameters and postoperative pathology were analyzed. The value of PET/CT in the efficacy evaluation was assessed. Results: The PET/CT assessment showed high consistency with postoperative pathological evaluation, yet the CT assessment showed low consistency with postoperative pathological evaluation. The (i)RECIST and PERCIST criteria showed statistically significant differences (p < 0.001). The postoperative pathological response was negatively associated with ΔSUVmax (%) (r = − 0.812, p < 0.001), ΔSUVmean (%) (r = − 0.805, p < 0.001), and ΔSUVpeak (%) (r = − 0.800, p < 0.001). The cut-off values of 75.8 for ΔSUVmax (%), 67.8 for ΔSUVmean (%), and 74.6 for ΔSUVpeak (%) had the highest sensitivity and specificity. Conclusion: The PERCIST criteria are more sensitive and accurate than (i)RECIST criteria to identify more responders when evaluating the response of neoadjuvant immunotherapy plus chemotherapy for NSCLC. PET/CT shows high accuracy in predicting postoperative pathological response. Our study shows the important role PET/CT plays in the efficacy evaluation of NSCLC patients undergoing neoadjuvant immunotherapy plus chemotherapy, as well as in predicting the prognosis and guiding postoperative treatment. Clinical relevance statement: Neoadjuvant immunotherapy plus chemotherapy is highly effective in the treatment of non-small-cell lung cancer. And PET/CT played an important role in the efficacy evaluation following neoadjuvant immunotherapy plus chemotherapy for non-small-cell lung cancer. Key Points: • Neoadjuvant immunotherapy plus chemotherapy is highly effective in the treatment of NSCLC. • The PERCIST criteria are more sensitive and accurate than (i)RECIST criteria to identify more responders when evaluating the response of neoadjuvant immunotherapy plus chemotherapy for NSCLC. • PET/CT played an important role in the efficacy evaluation; ΔSUVmax (%), ΔSUVmean (%), and ΔSUVpeak (%) following neoadjuvant immunotherapy plus chemotherapy for NSCLC had high consistency and strong correlations with postoperative pathology. [ABSTRACT FROM AUTHOR]