Zearalenone (ZEA), a mycotoxin mainly synthesized by Fusarium graminearum and F. culmorum is a widespread contaminant of several important crops such as wheat, maize, and paddy causing major plant diseases. Environmental factors such as rain and wind aids in the dispersal of ZEA in the soil and waters which affects aquatic lifes. ZEA causes detrimental health effects such as hyper-oestrogenism and premature abortions to human and animals when contaminated crops are ingested. Hence, it is vital to detect ZEA as early precautionary step in lowering the risks related with the health impairment to human and animals, as well as environmental contamination. Conventional methods are time-consuming and complex, thus, this study aimed on developing a highly sensitive biosensor using graphene-nickel decorated with 'rose petal' shaped iron nanoflowers (GNINF) as the transducer and aptamer as the bioreceptor. Low-pressure chemical vapour deposition is used to grown 3D-graphene followed by electrochemical deposition of iron (II) sulphate on its surface to form iron nanoflowers. Immobilisation of chemical and biomolecules were done using the layer-by-layer technique. Field-Emission Scanning Electron Microscopy showed prominent 'rose petal' shaped nanoflowers on the graphene surface. This unique assembly creates large surface area for immobilisation and better electric charge transfer on the material surface. The existence of hydroxyl group on the surface of GNINF also plays a role as linker to the surface. Besides, the sensitivity of the aptasensor was characterised using electrochemical impedance spectroscopy. The limit of detection achieved in this study is 1 fg ml-1 and the linear range is 1 fg ml-1 to 1 ng ml-1, which is highly sensitive than most reported biosensors. Overall, this highly sensitive aptasensor is a straightforward and cheap alternative for detecting ZEA in crops and the environment. © Published under licence by IOP Publishing Ltd.