unassigned: Zinc finger of the cerebellum 5 (ZIC5) has been found to be abnormally expressed in a variety of tumors. This study aimed to reveal the expression and functional mechanism of ZIC5 in hepatocellular carcinoma (HCC). unassigned: Analysis of ZIC5 expression in various tumors and its relationship with survival were derived from The Cancer Genome Atlas (TCGA) database. Cell counting kit-8 (CCK-8) and colony formation assays were performed for the detection of HCC cell proliferation. Differentially expressed genes (DEGs) after ZIC5 overexpression in Huh1 cells were determined by RNA sequencing. Western blot assays were conducted to detect the protein levels of c-Myc, Bcl2, p21, E-cadherin, N-cadherin, vimentin, and collagen type I alpha 1 (COL1A1). unassigned: Dramatically increased expression of ZIC5 was observed in various tumor tissues, including HCC. Pearson's correlation analysis revealed that the mRNA levels of ZIC5 had a positive correlation with the mRNA levels of MKI67 in HCC tissues. Patients with high ZIC5 expression had a shorter overall survival time. Moreover, ZIC5 overexpression promoted HCC cell proliferation. Then, we found that COL1A1 was significantly upregulated by ZIC5 overexpression to promote the proliferation, migration, and invasion of HCC cells. unassigned: ZIC5 could accelerate the proliferation, migration, and invasion of HCC cells through upregulating COL1A1. This is the first report that ZIC5 and COL1A1 are intrinsically linked, expanding new research ideas for subsequent HCC research.