Background: Randomized evidence comparing newer-generation drug-eluting stents for multivessel percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI) is limited. We sought to investigate clinical outcomes in STEMI patients undergoing multivessel PCI with thin-strut biodegradable polymer sirolimus-eluting stents (BP-SES) versus durable polymer everolimus-eluting stents (DP-EES). Methods: We performed a subgroup analysis of the BIOSTEMI (NCT02579031) randomized trial, which included individual patient data from STEMI patients enrolled into the BIOSCIENCE (NCT02579031) study. STEMI patients randomly allocated to BP-SES or DP-EES were divided into those undergoing multivessel versus culprit lesion-only PCI. The primary endpoint was target lesion failure (TLF), a composite of cardiac death, target vessel myocardial re-infarction or clinically indicated target lesion revascularization (TLR), within 24 months. Results: Among 1707 STEMI patients, 145 patients underwent multivessel PCI. At 2 years, TLF occurred in 2 patients (2.8%) treated with BP-SES and 13 patients (18.7%) treated with DP-EES (hazard ratio [HR], 0.14; 95% confidence interval (CI), 0.03-0.61; p = 0.009) in the multivessel PCI group, and in 40 (5.3%) and 61 (8.2%) patients treated with BP-SES and DP-EES respectively (HR, 0.64; 95%CI, 0.43-0.96; p = 0.03; p for interaction = 0.050) in the culprit lesion-only PCI group. In the multivessel PCI group, the rates of clinically indicated TLR (0% vs. 12.4%) and target vessel myocardial re-infarction (0% vs. 4.6%) at 2 years were lower in patients treated with BP-SES compared with DP-EES. Conclusion: In a subgroup analysis of the BIOSTEMI trial, BP-SES were associated with lower 2-year TLF rates compared to DP-EES in STEMI patients undergoing multivessel PCI.