Epithelial-to-mesenchymal transition (EMT) plays a critical role in the transformation of epithelial cells into a mesenchymal state. This process is significant in various biological contexts, including organ development, wound healing, and cancer progression. The aim of this chapter is to elucidate the role of EMT in gastrointestinal and gynecological cancers, its contribution to cancer progression and metastasis, and its implications for therapeutic strategies. EMT is characterized by the loss of epithelial markers and the acquisition of mesenchymal markers, leading to increased cell motility and invasion. In gastrointestinal cancers, EMT is associated with poor prognosis and resistance to chemotherapy. Subtypes of gastric and colorectal cancers demonstrate varying EMT characteristics, influencing their clinical outcomes. In gynecological cancers, EMT contributes to tumor progression, metastasis, and chemoresistance. Key transcription factors like Snail, Twist, and Zeb1 regulate EMT, while the tumor microenvironment, including hormones and hypoxia, significantly influences this process. EMT also plays a pivotal role in cancer stem cell properties and therapy resistance, with implications for targeted therapeutic approaches. EMT is a fundamental process in cancer progression, influencing metastasis, therapy resistance, and cancer stem cell properties. Understanding the molecular mechanisms and regulatory networks of EMT can inform the development of targeted therapies. Therapeutic strategies that inhibit EMT or reverse mesenchymal traits to epithelial characteristics hold promise in improving treatment efficacy and patient outcomes. However, careful consideration is required to balance the impact on normal physiological processes and avoid adverse effects.