A 4 mo old intact male kitten was presented for chronic regurgitation and failure to thrive after weaning to dry food. Esophageal dilatation and severe diffuse proliferative lesions of the esophageal mucosa were found via radiography and esophagoscopy, respectively. Histopathologic examination revealed severe, chronic, diffuse, hyperplastic eosinophilic and mastocytic esophagitis. Eosinophilic infiltrates were prominent, with a mean of 29.8 eosinophils per high power field, supportive of eosinophilic esophagitis (EoE). Significant clinical improvement was seen with dietary modification using a hydrolyzed diet. The addition of glucocorticoids did not result in further improvement in clinical signs. Repeat histopathology showed near resolution of eosinophilic infiltration. EoE is an uncommon and rarely reported condition in dogs and cats. Diagnosis involves histopathologic confirmation and exclusion of other causes of eosinophilic infiltration within the esophagus. This case report demonstrates the importance of biopsy in identification of EoE and the efficacy of dietary modification in the treatment of this disease in a kitten.