Objective To examine the association between programmed cell death ligand 1 (PD-L1) expression and venous thromboembolism (VTE) risk in lung cancer patients treated with immune checkpoint inhibitors (ICIs). Methods We enrolled adults with lung cancer who initiated ICIs between January 2018 and March 2022 at West China Hospital of Sichuan University. The included patients were divided into PD-L1 TPS<50% group and PD-L1 TPS≥50% group. Clinical outcomes including VTE, pulmonary embolism (PE), and deep venous thrombosis (DVT) were evaluated with cox regression models. Results Of the 519 lung cancer patients receiving ICIs finnaly analyzed (347 cases with PD-L1 TPS<50%; 172 cases with PD-L1 TPS≥50%), VTE developed in 48 cases (9.2%) during the 12-month follow-up, of which 41 cases (7.9%) had DVT, 4 cases (0.8%) had PE, and 3 cases (0.6%) had DVT and PE. A higher incidence of VTE was observed in TPS<50% group versus TPS≥50% group (P=0.026), whereas there was a trend toward an increased rate of DVT, which was not statistically significant (P=0.052). Significant differences in PE were not found (P=0.152). After multivariable adjustment, PD-L1 TPS<50%, ECOG PS≥2, chronic obstructive pulmonary disease, and VTE history were associated with an increased VTE risk (P<0.05). Conclusion VTE occurred in 9.2% of ICI-treated lung cancer patients. PD-L1 TPS<50% was associated with an increased risk of VTE, which should be identified, prevented and intervened early in clinical practice.