Annexin A3 participates in various biological processes, including tumorigenesis, drug resistance, and metastasis. The aim of this study was to investigate the expression of Annexin A3 in gastric cancer and its relationship with cell differentiation, migration, and invasion of gastric cancer cells. Annexin A3 expression in gastric cancer tissues was detected by quantitative real-time PCR and Western blotting. The proliferation of gastric cancer cells was measured by the MTT assay. Cell migration and invasion were determined via wound healing and transwell assays, respectively. Knock down of endogenous Annexin A3 in gastric cancer BGC823 cells was performed using siRNA technology. The expression of Annexin A3 was significantly upregulated in gastric cancer tissues, and negatively correlated with the differentiation degree. Silencing of endogenous Annexin A3 suppressed the proliferation, migration, and invasion of BGC823 cells. Additionally, the expression of p21, p27, TIMP-1, and TIMP-2 was upregulated, and the expression of PCNA, cyclin D1, MMP-1, and MMP-2 decreased in cells treated with Annexin A3-siRNA. Annexin A3 was upregulated in gastric cancer cells. Deletion of endogenous Annexin A3 significantly inhibited gastric cancer cell proliferation, migration, and invasion.