Bromodomain containing protein 4 (BRD4) has been demonstrated to play a critical role in tumor progression. However, the expression and function of BRD4 in gallbladder cancer (GBC) are still unknown. In this study, we report that BRD4 expression level was significantly upregulated in GBC tissues and GBC cell lines. We explored the correlation between BRD4 levels and clinicopathological data of GBC patients. The high expression level of BRD4 was notably correlated with the poor prognosis of GBC patients. Knockdown of BRD4 suppressed proliferation and migration in NOZ and EH-GB1 cells. The depletion of BRD4 in GBC cell lines resulted in obvious cell apoptosis and downregulated the expression levels of Bcl-2, p-PI3K and p-AKT. In vivo, tumor volumes of nude mice were significantly decreased in BRD4 silenced group. Our data suggested that downregulation of BRD4 in GBC cells induced apoptosis by PI3K/AKT pathway. Inhibition of BRD4 expression may be a novel therapeutic strategy for patients with GBC.