Urinary KIM-1 is an ideal biomarker for acute kidney injury diagnosis. The proof-of-concept is demonstrated by utilizing the hydroxyapatite derived from natural fish scales as an electrode material, where the sensing of KIM-1 is shown to be possible for the first time with a linear range from 0.01 to 0.20 μg mL⁻¹ and a detection limit of 0.017 μg mL⁻¹ under model conditions; proof-of-concept is demonstrated in spiked urine.