Rho-associated coiled-coil-containing protein kinase 2 (ROCK2) has been known as an effector for the small GTPase Rho and plays an important role in tumor progression and metastasis. However, the effect of ROCK2 in gastric cancer (GC) has not been identified. This study showed that ROCK2 expression significantly increased in clinical GC tissues compared with adjacent non-cancer tissues. Immunohistochemistrical analysis showed that high expression of ROCK2 was correlated with tumor grade, tumor-node-metastasis stage, infiltration depth, lymph node invasion and Ki-67, and predicted poor prognosis in 135 gastric cancer specimens. In addition, we found that upregulated ROCK2 promoted proliferation, metastasis and invasion of GC cells, while ROCK2 knockdown led to the opposite results in vitro by Cell Counting Kit-8 (CCK-8) assay, colony formation assays, flow cytometric analysis and trans-well assays. Our findings supported that ROCK2 was a significant protein in the progress of GC and would provide a novel promising therapeutic strategy against human GC.