Background: Both drug-eluting bead transarterial chemoembolization (DEB-TACE) and hepatic arterial infusion chemotherapy (HAIC) are recommended for unresectable colorectal liver metastases (CRLM) treatment. However, the combined application of DEB-TACE and HAIC is not widely accepted. The aim of this single-center retrospective study was to evaluate the efficacy and safety of Irinotecan-eluting HepaSphere chemoembolization combined with HAIC for unresectable CRLM. Methods: Patients with age older than 18 years, histologically confirmed CRLM and treated with Irinotecan-eluting HepaSphere chemoembolization plus HAIC from Oct 2020 to Jan 2022 were enrolled. Patients who had synchronously received other local treatments were excluded. Hepatic progression-free survival (hPFS) and PFS were calculated using Kaplan-Meier method. Adverse events (AE) were evaluated with CTCAE 5.0. Results: The eligible population was 101, composed of 66 males and 35 females. Among them, 54% patients had one of KRAS or NRAS or BRAF gene mutation and ECOG of 62% patients was 1. In addition, 59% patients were refractory to second standard line or above systemic therapy and mean interventional treatment cycles were 3.3. As the follow-up cutoff date was Dec 31, 2022, median duration of follow-up was 17.9 months (95% CI,16.185-19.615). Median hPFS was 8.7 months (95% CI, 6.744-10.658) while median PFS was 6.2 months (95% CI, 5.048-7.352). For the patients who were refractory to second line or above systemic therapy, hPFS and PFS was 6.2 months (95% CI, 4.899-7.501) and 5.2 months (95% CI, 3.682-6.718) respectively. Overall survival has not been reached yet. There were 7 patients achieved clinical complete response. Overall response rate was 41.6% and disease control rate was 82.2%. There was no treatment-related death. 28 patients (27.7%) experienced grade 3 or higher toxicities. The most common treatment related AE were aspartate transaminase/alanine transaminase elevation (41.6%) and bilirubin elevation (40.6%). The hematologic AE included anemia (27.7%), leukopenia (27.7%), neutropenia (14.9%) and thrombocytopenia (28.7%). Conclusions: The combination of Irinotecan-eluting HepaSphere chemoembolization and HAIC is effective and safe for unresectable CRCLM, even for patients who are refractory to second or above systemic therapy, indicating it is a promising regional treatment with improved outcome.