Squamous esophageal epithelium adapts to acid reflux-mediated injury by proliferation and differentiation. Induction of the Wnt-antagonist, Dickkopf-1 (Dkk1) is involved in tissue repair during inflammation and cellular injury. In this study, we aimed to identify the biological role of Dkk1 in human reflux-esophagitis with respect to cell growth and regulation of Wnt-signaling. Esophageal biopsies from reflux-esophagitis patients and healthy individuals were characterized for Dkk1 expression. Role of Dkk1 in response to acid-mediated epithelial injury was analyzed by utilizing squamous esophageal epithelial cell lines (EPC1-, EPC2-hTERT and HEEC). Dkk1 was significantly overexpressed in human reflux-esophagitis tissue compared to healthy esophageal mucosa at transcriptional and translational level. Following acute and chronic acid exposure (pH 4), esophageal squamous epithelial cell lines expressed and secreted high levels of Dkk1 as response to stress-associated DNA injury. Human recombinant Dkk1 inhibited epithelial cell growth and induced cellular senescence as demonstrated by reduced cell proliferation, G0/G1 cell cycle arrest, elevated senescence-associated β-galactosidase activity (SA-β-gal) and up-regulation of p16. Acid pulsing induced Dkk1-mediated senescence, which was directly linked to the ability of Dkk1 to antagonize the canonical Wnt/β-catenin signaling. In healthy esophageal mucosa, Dkk1 expression was associated with low expression of transcriptional active β-catenin, while in reflux-esophagitis tissue, Dkk1 overexpression associated with increased SA-β-gal activity and p16 up-regulation. These data indicate that in human reflux-esophagitis, Dkk1 functions as a secreted growth-inhibitor by suppressing Wnt/β-catenin signaling and promoting cellular senescence. Taken together, our findings suggest a significant role for Dkk1 and cellular senescence in esophageal homeostasis during reflux-esophagitis.