Early detection of contaminants is of prime importance in the agricultural and food industries. Until recently real-time analysis of contaminated samples has been limited due to non-portability of sophisticated laboratory instruments and need of skilled personnel. Therefore, cheap, portable and easy to use biosensors are needed. Nanotechnology provides advanced biosensors as a result of novel nanofabrication and nanobioconjugation techniques. In particular, enzymatic nanobiosensors display ultrasensitivity and quick detection time in real-time analysis. Reported detection limits are at the nanomolar to picomolar level for contaminants analysed by enzymatic nanobiosensors. This review summarises nanobiotechnological advances in the agricultural and food industry, with focus on the detection of pesticides and food-borne contaminants.