Non-small cell lung cancer (NSCLC) is the most pervasive lung cancer subtype. Recent studies have shown that immune checkpoint inhibitors achieved favorable clinical benefits in resectable NSCLC; however, the associated mechanism remains unclear. The role of T cells in antitumor immunity has received considerable attention, while the antitumor effects of tumor-infiltrating B cells (TIBs) in NSCLC remain poorly understood. Here, we conducted a single-cell RNA-seq analysis of immune cells isolated from 12 patients with IIIA NSCLC to investigate B cell subtypes and their functions following neoadjuvant chemoimmunotherapy. We confirmed the simultaneous existence of the four B cell subtypes. Among them, memory B cells were found to be associated with a positive therapeutic effect to neoadjuvant chemoimmunotherapy. Furthermore, we found that G Protein-Coupled Receptor 183 (GPR183) was most prevalent in memory B cells and associated with a positive therapeutic response. Multiplex immunofluorescence and flow cytometry experiments in an additional cohort of 22 treatment-naïve and 30 IIIA/IIIB NSCLC patients treated with neoadjuvant chemoimmunotherapy verified these findings. Overall, our analysis revealed the functions of TIBs and their potential effect on clinical treatment in NSCLC.Keywords: GPR183; Non-small cell lung cancer; memory B cells; neoadjuvant chemoimmunotherapy.