This paper reports label free sub-femtomolar detection of cardiac biomarker troponin T using ZnSnO 3 perovskite nanomaterial based electrochemical biosensors. Herein, we have demonstrated two separate synthesis schemes for the perovskite material, one being a hydrothermal synthesis method, and the other being electrochemical deposition. In this work, for the electrochemical detection of troponin T with the hydrothermally synthesized ZnSnO 3 , we have used a glassy carbon electrode (GCE), on to which the nanomaterials are dropcasted so as to create a heterogeneous working electrode. In a separate scheme, we have used indium tin oxide coated polyethylene terephthalate (ITO/PET) substrates as the working electrodes, on to which a thin film of ZnSnO 3 nanomaterial has been deposited electrochemically. Subsequently, the capture antibodies corresponding to the targeted cardiac troponin T are immobilized on to the surface functionalized working electrodes using NHS/EDC chemistry. The electrochemical detection of the target analyte has been performed in the concentration range of 1 fg mL -1 to 1 μg mL -1 , using electrochemical impedance spectroscopy. For the GCE and ITO/PET based bioelectrodes, the approximated limits of detection are found to be 0.187 fg mL -1 and 0.571 fg mL -1 respectively, whereas the respective values of sensitivity of the same are 35.25 kΩ (μg mL -1 ) -1 cm -2 and 8.813 kΩ (μg mL -1 ) -1 cm -2 . © 2019 The Royal Society of Chemistry.