In this work, we demonstrate a novel, label-free flexible plastic based platform for immunosensing application. This nanobiosensor platform comprises of mercaptopropionic acid functionalized electrospun zinc oxide nanofiber modified flexible plastic film for covalent conjugation of protein. The highly oriented zinc oxide nanowires were synthesized by simple, low cost electrospinning technique and electrophoretically deposited on the ITO coated flexible plastic sheet. The performance of nanobiosensor platform is validated by using BSA-Anti BSA interaction as a model system. The zinc oxide nanowire modified flexible biosensing platforms have been characterized using scanning electron microscopy and atomic force microscopy. The fabricated flexible plastic based immunosensor shows a remarkable detection limit of 100fg/mL in the wider detection range of 100 fg/mL-100 μg/mL. To the best of our knowledge, this is the first time that zinc oxide nanofiber modified flexible plastic substrate have been used to develop immunosensing application and efforts should be made to explore this flexible immunosensor platform for the detection of several important biomarkers for point of care (POC) diagnostics. © 2016 IEEE.