Objective To knock out the high-mobility group AT-hook 2 (HMGA2) gene using the CRISPR/ Cas9 system in HepG2 cells and investigate the effect of HMGA2 knockout on the growth, proliferation, migration, and invasion of hepatoma carcinoma cells. Methods The human HMGA2 gene sequence was obtained from GenBank. Two sgRNAs were designed for each of the first and second exons of the HMGA2 gene using online sgRNA design software. The recombinant sgRNA vectors sgE1 and sgE2 were constructed and transfected into HepG2 cells to obtain the HMGA2^{- / -} cell line. The effects of HMGA2 knockout on the growth and proliferation of HepG2 cells were investigated via CCK8 and clone formation assays, while the migration and invasion abilities were measured using Transwell assays. Results Compared with wild-type HepG2 cells, the knockout cell line showed reduced proliferation, clone formation (121. 83 ± 21. 68 vs 59. 50 ± 20. 68, P< 0. 01), invasion (359. 67 ± 32. 53 vs 245. 61 ± 24. 23,P< 0. 05), and migration ( 251. 33 ± 43. 43 vs 47. 00 ± 10. 00, P< 0. 01). Conclusions HMGA2 knockout in hepatoma carcinoma cells inhibited both cellular proliferation and tumor metastasis in vitro. Therefore, HMGA2 may constitute a target for hepatoma gene therapy.