Hyperammonemic encephalopathy (HE) can be broadly defined as an alteration in the level of consciousness due to elevated blood ammonia level. While hepatic cirrhosis is the most common cause of HE, non-hepatic causes like drugs, infections, and porto-systemic shunts can also lead to the presentation. In this case, we highlight an unusual occurrence of recurrent non-cirrhotic HE from obstructive urinary tract infection (UTI) with urea-splitting micro-organisms in an elderly male patient. The patient exhibited altered mentation, and elevated ammonia levels with normal hepatic function at presentation. Urine culture revealed Proteus mirabilis resistant to extended spectrum beta-lactamases (ESBL). Successful management of obstructive UTI was achieved through Foley’s catheterization and intravenous (IV) antibiotics, resulting in the resolution of HE. This outcome further supports the significance of UTI as a potential cause of hyperammonemia. Thus, UTI as one of the non-hepatic causes of hyperammonemia should always be explored among elderly patients presenting with altered mentation.