Accumulating evidence indicates that KIAA1199 plays a vital role in tumor progression. However, the role of KIAA1199 in hepatocellular carcinoma (HCC) still remains unknown. In this study, we found that KIAA1199 was upregulated in human HCC tissues and in highly metastatic HCC cell lines. Furthermore, the expression of KIAA1199 was significantly correlated with tumor size and metastasis in HCC. Knockdown of KIAA1199 inhibited cell proliferation and migration in vitro, and suppressed tumorigenicity and lung metastasis in vivo. In addition, silencing of KIAA1199 induced G1 phase arrest by reducing cyclinDl expression. Moreover, KIAA1199 knockdown induced apoptosis by activating endoplasmic reticulum (ER) stress, which was based on the upregulation of ER stress markers, activating transcription factor 4 (ATF4) and CAAT/enhancer-binding protein homologous protein (CHOP). In conclusion, our data demonstrated that KIAA1199 knockdown inhibited the growth and metastasis of HCC.