Foreign body aspiration can affect individuals of all ages and lead to symptoms such as dyspnea, coughing, and wheezing. Complications may arise from the physical and chemical properties of the aspirated material as well as the duration of retention. This case study reports the early bronchoscopic and pathological findings of a 38-year-old male patient who aspirated walnuts. The patient underwent flexible bronchoscopy 14 h after aspiration, and a piece of walnut was successfully removed from the intermediate bronchus. During the procedure, the bronchial mucosa appeared extremely irregular and yellowish-green in color. Follow-up bronchoscopy one month later revealed regression of the previously observed granulation tissue. This case highlights the importance of early intervention in foreign body aspiration cases, especially with substances that can rapidly and intensely react with mucous membranes such as walnuts.