Acute kidney injury is a common complication in patients with cancer. Obstructive uropathy is a rare complication of gastric cancer and occurs mainly during treatment. Moreover, obstructive uropathy is rarely complicated by acute renal injury and thus requires emergency treatment. We report a rare case of anuric acute kidney injury that was actually obstructive uropathy secondary to gastric adenocarcinoma. Based on this case and literature review, malignancy should be considered in any patient not known to have cancer who presents with acute kidney injury caused by obstructive uropathy. This presentation reflects an advanced stage of malignancy. Non-enhanced computed tomography is valuable and should be the initial imaging study for diagnosing the obstruction and its cause. Early diagnosis and relief of the obstruction are associated with better recovery of the renal function.