Blocking the PD-L1/PD-1 interaction with an antibody produces a durable response in patients with diverse advanced cancers. However, it remains elusive on whether the engagement of PD-L1 to PD-1 leads to tumor-intrinsic signaling. In this study, we aim to explore novel protein substrates participating in transducing this tumor-intrinsic PD-L1 signaling. To this end, we performed a BioID (proximity-dependent biotin identification) assay, in which we fused PD-L1 to BirA* (a promiscuous mutant of bacterial biotin ligase BirA) and overexpressed it in the lung adenocarcinoma A549 cell line. Through streptavidin affinity capture and mass spectrometry analysis, we identified 57 candidate proteins including 18 PD-L1/PD-1-interaction-dependent neighbors. In addition to this, 9 out of 57 candidates were involved in the EGFR signaling pathway, which is known to play a critical role in tumorigenesis and multiple therapeutic resistances of lung cancer. This study will provide a new insight in understanding tumor-intrinsic PD-L1-signaling effectors of lung cancer.