Simple Summary Feline gingivostomatitis is a common condition affecting the oral cavity of cats, characterized by severe mucosal inflammation. The etiopathogenesis remains not fully clear, but it is known to be multifactorial, involving alterations in immune response which may be related to infectious agents. Other potential triggers include food sensitivity and genetic and environmental factors. This study followed a cat refractory to conventional treatment who was placed on an elimination diet. After the implementation of the elimination diet, the cat showed remission of oral lesions. This report aims to highlight the importance of recognizing food sensitivity as a significant factor in maintaining the chronicity of the disease and how dietary management and switching to a hypoallergenic diet can aid in controlling the lesions. To the authors' knowledge, this is the first documented case demonstrating the impact of food sensitivity on the progression of feline gingivostomatitis. The findings emphasize the importance of incorporating nutritional considerations into the comprehensive management of this challenging condition.Abstract Feline stomatitis or gingivostomatitis is a chronic inflammatory condition affecting approximately 0.7% of patients. The cause is multifactorial, involving infectious agents, genetic factors, and environmental influences. Therapeutic strategies include pharmacological and surgical interventions to controlling inflammation and enhancing patient quality of life. There are discussions in the literature regarding the potential involvement of adverse food reactions as a contributing factor to oral cavity lesions, without clear evidence. This case report describes the control of gingivostomatitis with a hypoallergenic diet in a cat that had oral lesions and who was refractory to conventional treatment with prednisolone and cyclosporine, even after periodontal treatment and partial tooth extraction. After 30 days of dietary change, there was complete remission of the lesions. The animal was then re-exposed to the previous food, with new lesions appearing after 7 days. Upon returning to the hypoallergenic food, there was new remission of the lesions. This report suggests that food sensitivity may play a role in the control of feline gingivostomatitis, as periods of hypoallergenic diet coincided with the remission of the condition, even without changes in medication. It reinforces the importance of investigating adverse food reactions as clinical signs in the oral cavity of cats.