We report an ultra-selective biosensor for detection of fibrinogen (fib) using AlFeO3 nanospheres modified screen-printed carbon electrode (AFO/SPCE) via electrochemical impedance spectroscopy (EIS). The orthorhombic phase and nanospheres-like morphology of hydrothermally grown AlFeO3 are confirmed via X-Ray diffraction (XRD) and scanning electron microscopy (SEM) imaging, respectively. The sensor exhibits excellent selectivity, sensitivity and low limit of detection (LOD) of 14 ng mL-1 with a wide dynamic range from 3~μ g mL-1 to 340× 10 3μ g mL-1 which is more suitable for detecting both the deficiency and excess level of fib in the human blood. The decrease in charge transfer resistance (R_ct) with an increase in fib concentrations can be attributed to the strong interaction and electrooxidation of fib molecules forming protein carbonyl groups at the surface of the electrode with enhanced electrical conductivity. This is a report on the low-cost, simple electrochemical impedance sensor using perovskite AlFeO3 for reliable and rapid sensing of fib which shows great potential for developing biosensors for healthcare. © 2001-2012 IEEE.