Background: Upper tract urothelial carcinoma (UTUC) frequently exhibits hematuria, flank pain, clot colic, and flank pain. They are very rarely detected as incidental renal masses in imaging studies. On a computed tomography (CT) scan, they usually appear as soft tissue masses with low-grade enhancement and a filling defect. Radical nephroureterectomy is the standard treatment for high-grade UTUC or large-volume low-grade UTUC. Ureteroscopic laser fulguration can be offered to low-grade, ≤2 cm UTUC, or sometimes for high-grade high volume disease in those with solitary kidneys. We present a case study of an incidentally detected large UTUC (3 cm) that was fulgurated using a thulium fiber laser (TFL). Case Description: An 86-year-old female presented with symptoms of gastritis. CT scan done for further evaluation detected 3 cm urothelial mass arising left lower calyx and left renal pelvis. Endoscopic evaluation and biopsy confirmed left low-grade UTUC. Tumor adequately fulgurated using TFL. Because of patient’s advanced age and asymptomatic presentation, she refused radical nephrectomy and opted for endoscopic treatment and surveillance. She is undergoing 3 monthly surveillance cystoscopies with no evidence of recurrence over last 15 months. Conclusions: It is very unusual for large UTUC to have asymptomatic presentation. Appropriately selected patients who are not candidates for radical cystectomy can be managed with ureteroscopic laser fulguration.