Ectopic gastric mucosa has been described at various locations of the body, including all levels of the gastrointestinal tract. However, this finding is rare in the rectum and anus, with 38 reported cases. In only six cases, including the present one, has the heterotopic tissue been located within 2 cm of the dentate line. We report a case of gastric heterotopia discovered in a 21-year-old male who presented with anal pain and pruritus. Flexible sigmoidoscopy demonstrated an anal polyp, and biopsy confirmed fundic-type gastric tissue. A (99m)technetium-pertechnetate scan confirmed increased uptake in the anus. After minimal clinical improvement with proton-pump inhibitors, the patient underwent local surgical excision and remains symptom-free at a follow-up of 9 months. We review the potential etiologies, clinical manifestations, treatment options, and patient outcomes.