Hepatocellular carcinoma (HCC) patients with macrovascular invasion (MVI) have dismal prognosis and there are no standard perioperative therapies. This phase 2 trial (ChiCTR2000036385) aimed to investigate the activity and safety of perioperative tislelizumab plus intensity modulated radiotherapy (IMRT) for resectable HCC with MVI. Thirty treatment-naïve patients with MVI received 3 cycles of tislelizumab intravenously (200 mg, every three weeks) and concurrent IMRT (45 Gray in 15 fractions). Primary endpoints were the overall response rate (ORR) and overall survival (OS). Secondary endpoints were the proportion of patients with a complete or major pathological response (pCR or MPR), recurrence-free survival (RFS) and safety. Of patients enrolled, 15 (50%) underwent curative surgery followed by adjuvant tislelizumab. The ORR was 30.0% (90% CI 16.6%-46.5%) and the median OS was 18.7 months. Of the 15 patients underwent surgical resection, 10 (66.7%) achieved pCR or MPR and 8 (53.3%) remained recurrence-free. The median RFS were not reached with a median follow-up of 21.77 months (95% CI 12.50-31.03) post-surgery. 4 (13.3%) patients experienced grade 3 treatment-related adverse events. The most common events were thrombocytopenia, leukopenia, and anemia. The trial has met the pre-specified endpoints, and these results support further studies of perioperative immunotherapy plus radiotherapy in HCC.