Background: Double-J (DJ) stent is an integral part of urologic practice. DJ stents can have numerous complications such as persistent irritative symptoms, encrustations, and up and down migrations within the pelvicaliceal system (PCS), but displacement outside the urinary tract is rare. We are presenting a unique case of DJ stent lying outside the PCS for more than a decade. Case Presentation: A 46-year-old female presented with left flank pain and dysuria. She had undergone percutaneous nephrolithotomy in the left side 11 years ago. Imaging studies revealed a forgotten DJ stent with proximal part lying in the PCS with dense encrustations and the distal coil in the retroperitoneum at the level of the contralateral sacroiliac joint with the shaft crossing the midline at fourth lumbar vertebral level. The malpositioned forgotten stent was removed intact using the multimodal endourologic technique. During follow-up, the patient had prompt relief of symptoms and a preserved renal unit. Conclusion: To the best of our knowledge, this is the first report of malpositioned and forgotten DJ stent for more than a decade with lower end lying near the opposite lower ureter managed effectively by an endourologic method.