Epidermal growth factor receptor (EGFR) exon 20 insertion is not associated with sensitivity to EGFR tyrosine kinase inhibitors and chemotherapy. Here, we report the case of a 41-year-old man who presented a right lower lobe nodule and mediastinal lymph node enlargement diagnosed as EGFR exon 20 insertion adenocarcinoma with high-expression programmed cell death ligand 1 (PD-L1). He showed stable disease to chemoradiation treatment at the primary tumor site. However, durvalumab treatment has good response. Non-small cell lung cancer with EGFR exon 20 insertion and high PD-L1 expression may be treated with immunotherapy exposure.