The successful integration of nanotechnology as a platform for food sensors offers tremendous benefits in detecting contaminants, particularly in their applications for food quality and safety. The sensors based on nanomaterials (nanosensor), both chemical sensors (chemical nanosensors) and biosensors (nanobiosensors), can be used online and integrated into existing manufacturing process and distribution line or off-line as rapid, simple, and portable, as well as disposable, sensors for food contaminants. Food contaminants could be residues of pesticides, veterinary and human drugs, microbial toxins, preservatives, contaminants from food processing and packaging, and other residues. This milieu of compounds can pose difficulties in the detection of food contaminants. Nanosensors with their novel uses are the emerging method that could be used for the detection of many food contaminants, even mycotoxins and many food allergens. Whether it used as online or off-line, the nanosensor can be integrated with wireless technology and used for real-time transmission of contaminant alarm or test results to remote servers, providing rapid screening and reporting. Thus nanosensors are more cost-effective, rapid, and more sensitive than instrumental and conventional procedures. Recent developments in nanosensors may provide more applications for their use in food contaminant detection. The future role of these nanosensors will become even more important as the food laboratory is faced with the increasing pressure to reduce cost, time, and complexity. The objective of this chapter is to give a general overview of the possible application of nanosensors in the food contaminant detection and analysis.