FAM3B has been suggested to play important roles in the progression of many cancers, such as gastric, oral, colon and prostate cancer. However, little is known about the role of FAM3B in human esophageal squamous cell carcinoma (ESCC). In the present study, we found that FAM3B expression was higher in ESCC tissues than in adjacent normal tissues. Using quantitative real-time polymerase chain reaction, we found similar results in cell lines. FAM3B expression was significantly related to T/TNM stage. Importantly, Kaplan-Meier analysis revealed that a high expression level of FAM3B predicted a poor outcome for ESCC patients. Overexpression of FAM3B inhibits ESCC cell death, increases oesophageal tumour growth in xenografted nude mice, and promotes ESCC cell migration and invasion. Further studies confirmed that FAM3B regulates the AKT-MDM2-p53 pathway and two core epithelial-to-mesenchymal transition process markers, Snail and E-cadherin. Our results provide new insights into the role of FAM3B in the progression of ESCC and suggest that FAM3B may be a promising molecular target and diagnostic marker for ESCC. © 2018 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.