AbstractGastric cancer (GC) is one of the most common gastrointestinal tumors. In this study, we assessed the biological role of Ras association domain family 1 isoform A (RASSF1A) in GC cells. Expressions of RASSF1A and the relationship of RASSF1A with epithelial–mesenchymal transformation (EMT)‐related proteins were assessed in five cell lines using Western blot. GC cells with RASSF1A overexpression were used to study sensitivity to cisplatin, migration, invasion, and the expression of EMT‐associated biomarkers. GC cells showed profound downregulation of RASSF1A expression compared with normal human gastric mucosal cells. High RASSF1A expression was associated with increased overall survival. Overexpression of RASSF1A regulates GC cells activity and the expression of EMT‐associated biomarkers. RASSF1A regulates E‐cadherin and Vimentin through P‐JNK pathway. Our results revealed that RASSF1A can inhibit the proliferation, migration, and invasion of GC cells via E‐cadherin. Our study provides insights for further research on GC.