INTRODUCTION AND IMPORTANCE: Klippel-Trenaunay syndrome (KTS) is a rare congenital disorder with an incidence of about 2-5:100 000. It is characterized by the triad of cutaneous hemangiomas, soft tissue or bone hypertrophy, and venous malformations. Gastrointestinal (GI) involvement in KTS, although uncommon, can lead to severe complications such as profuse GI bleeding. Our case highlights the challenges and management strategies of a patient with KTS. CASE PRESENTATION: A 5-year-old child presented with rectal bleeding since birth, accompanied by swelling and bluish discoloration on left flank, and multiple varicose veins on left leg. Examination revealed small hemangiomatous lesions scattered along the torso and trunk. Barium enema showed diffuse mucosal irregularity with polypoidal filling defects in the rectum and sigmoid colon. Doppler ultrasound revealed slow-flow vascular lesions in the left flank and leg without arteriovenous communication. Computed tomography (CT) scan showed diffuse cavernous hemangiomas in the descending colon, sigmoid colon, and rectum. Histopathology demonstrated numerous dilated, irregular vascular channels with calcification and hemosiderin-laden macrophages. CLINICAL DISCUSSION: GI tract cavernous hemangiomas can cause chronic bleeding and anemia, necessitating careful evaluation. Imaging modalities like CT and Doppler ultrasound are crucial for assessing vascular lesions. Surgical interventions, including partial proctocolectomy and colorectal anastomosis, effectively control bleeding and improve outcomes. A multidisciplinary approach is essential for managing such cases. CONCLUSION: This case underscores the importance of multidisciplinary management in KTS with GI bleeding. Effective diagnostic imaging and surgical treatment are key to managing severe complications and achieving successful outcomes. Long-term follow-up is crucial to monitor for recurrence and residual lesions.