Hyperammonemic encephalopathy is an under-recognized and potentially fatal complication of Roux-en-Y gastric bypass surgery. We present a case of a 42-year-old woman with no known history of liver disease who experienced worsening encephalopathy 1 year after bariatric surgery. She presented with elevated ammonia and severe encephalopathy requiring intubation. A complete workup led to the diagnosis of a urea cycle disorder. The patient was managed with lactulose, ammonia scavenging agents, and nutritional supplementation with a favorable outcome. We report this case to increase awareness of this condition and urge providers to maintain a high clinical suspicion in the appropriate setting.