Essential thrombocythemia (ET) is associated with an increased risk of thrombosis and autoimmune renal involvement. We report an extremely rare case of an acute kidney injury (AKI) in the presence of bilateral renal pelvises fibrosis in a patient with a proven diagnosis of ET. A 48-year-old male patient with a past medical history of mild chronic kidney disease and ET was admitted to our hospital with AKI. The patient discontinued his hydroxyurea treatment for the past 2 months and laboratory data showed increasing serum creatinine levels and platelet counts with increased renal sizes, severe hydrocalyx, and bilateral renal sinuses\' fibrosis in imaging. The patient started again on hydroxyurea therapy and showed improvement in all laboratory scales. ET and increased levels of platelet-derived growth factors could cause renal sinuses fibrosis and glomerulopathy. In ET patients with renal sinuses\' fibrosis and glomerulopathy, initiating cytoreductive therapy could improve the outcome.