Introduction: Signet ring cell carcinoma is a rare subtype of colorectal cancer with distinct clinical behavior. We present a case of large bowel obstruction secondary to signet ring cell carcinoma of the descending colon. Case Presentation: A middle-aged multiparous female presented with a 15-day history of progressive abdominal pain, constipation, vomiting, and fever. Imaging revealed nearcomplete luminal obstruction of the descending colon. Exploratory laparotomy with left hemicolectomy was performed. Histopathology confirmed signet ring cell carcinoma with serosal invasion and lymph node metastasis. Conclusion: This case highlights the aggressive nature of signet ring cell carcinoma and the importance of prompt diagnosis and treatment. Clinicians should maintain a high index of suspicion for this rare entity in patients presenting with large bowel obstruction.