Food poisoning causes significant discomfort to many people each year, with one of the main causes being the bacterium Escherichia coli O157:H7. Detecting pathogenic Escherichia coli O157:H7 in various types of food is crucial for ensuring food safety. Immunosensors have shown great potential as rapid, sensitive, and specific diagnostic tools for this particular illness because of their ability to use specific antigen–antibody interactions. This chapter provides a thorough examination of the progress and use of immunosensors for detecting E. coli O157:H7 in different types of food, such as dairy products, meat, fruits, and vegetables. This article provides a comprehensive elucidation of the basic concepts that form the basis of immunosensor function, with a particular focus on various transduction mechanisms, including optical, electrochemical, and piezoelectric approaches. This research investigates the potential of nanomaterials to reduce detection limits and increase sensor sensitivity. Additionally, it examines the difficulties associated with preserving the stability and functionality of antibodies under different nutritional circumstances. Case examples exemplify the pragmatic use of immunosensors and demonstrate their effectiveness in real-life situations. This chapter compares immunosensors to standard microbiological procedures, highlighting the benefits of immunosensors in terms of speed, mobility, and onsite testing capabilities. This discussion focuses on potential advancements in immunosensor technology, including the integration of wireless systems and the utilisation of multiplexed platforms for concurrent illness detection. These advancements have the potential to greatly improve food safety and monitor public health.