Juvenile polyps (JPs) are the most common polyps in pediatric patients. We present the case of an 18-year-old male patient with a giant solitary JP resembling solitary rectal ulcer syndrome (SRUS). The presenting history was rectal bleeding and symptoms of obstructed defecation syndrome. Colonoscopy revealed a polypoidal mass at the anorectal junction, with biopsy-confirmed SRUS. The symptoms worsened, and a protruding mass from the anus caused fecal incontinence. Pelvic magnetic resonance imaging showed a huge pedunculated mass occupying the low rectum with local compression of the urinary bladder. Transanal excision of the anal tumor was performed due to bleeding. A histopathological examination showed a JP with high-grade dysplasia. A histological examination to differentiate JPs and SRUS could be challenging based on a superficial forceps biopsy. Therefore, an excision biopsy is usually warranted with the understanding that adenomatous or malignant transformation is found in 5.6% to 12% of all JPs.