Food allergies are increasing and pose a serious risk to sensitive individuals. This allergy affects mostly underaged children and a small percentage of adults. There is no effective immune therapeutic approach for detecting the presence and protecting susceptible individuals. Conventional approaches such as PCR, ELISA, and chromatography have certain drawbacks, such as their high cost and time-consuming nature and the need for well-skilled individuals. By combining biosensors and nanoparticles, these methods have become more affordable, sensitive, selective, and time-efficient and can replace traditional methods. Food allergies are generally immune responses triggered by contact with specific foods. It is crucial to detect food allergens effectively and practically by monitoring food allergens via a point-of-care biosensor. An immunosensor is an antibody–antigen interaction-based method in which a specific allergen can be detected. In the immunosensor, the antibody–antigen reaction helps to find different allergens in foods such as soybean, peanuts, cow milk, cereal, eggs, and crustaceans. In this chapter, we discuss the different types of allergen-specific antibodies, such as monoclonal antibodies, polyclonal antibodies, and camelid-derived nanobodies, as well as allergens present in various foods. Owing to the efficiency, user-friendliness, and simplicity of immunosensors, they can be used in various foods to detect allergens.