Fam134b
(JK‐1, RETREG1) was first identified as an oncogene in esophageal squamous cell carcinoma. However, the roles of
FAM
134B during tumorigenesis of hepatocellular carcinoma (
HCC
) and in epithelial‐to‐mesenchymal transition (
EMT
) were previously unclear. In this study, we investigated the function of
FAM
134B in
HCC
and the related tumorigenesis mechanisms, as well as how
FAM
134B induces
EMT
. We detected the expression of
FAM
134B in a normal hepatic cell line,
HCC
cell lines, fresh specimens, and a
HCC
tissue microarray. A retrospective study of 122 paired
HCC
tissue microarrays was used to analyze the correlation between
FAM
134B and clinical features. Gain‐ and loss‐of‐function experiments, rescue experiments, Akt pathway activator/inhibitors, nude mice xenograft models, and nude mice lung metastasis models were used to determine the underlying mechanisms of
FAM
134B in inducing tumorigenesis and
EMT
in vitro
and
in vivo
. The expression level of
FAM
134B was highly elevated in
HCC
, as compared with that in normal liver tissues and normal hepatic cells. Overexpression of
FAM
134B was significantly associated with tumor size (
P
= 0.025), pathological vascular invasion (
P
= 0.026), differentiation grade (
P
= 0.023), cancer recurrence (
P
= 0.044), and portal vein tumor thrombus (
P
= 0.036) in
HCC
. Patients with high expression of
FAM
134B had shorter overall survival and disease‐free survival than patients with non‐high expression of
FAM
134B. Furthermore, knockdown of
FAM
134B with sh
RNA
s inhibited cell growth and motility, as well as tumor formation and metastasis in nude mice, all of which were promoted by overexpression of
FAM
134B. Our study demonstrated that
Fam134b
is an oncogene that plays a crucial role in
HCC
via the Akt signaling pathway with subsequent glycogen synthase kinase‐3β phosphorylation, accumulation of β‐catenin, and stabilization of Snail, which promotes tumorigenesis,
EMT
, and tumor metastasis in
HCC
.