Global population growth and rising food consumption pose significant concerns for food safety. Crop loss is mostly caused by several diseases, including bacterial, fungal, and viral diseases. Diagnosis of pathogens that is accurate and quick is crucial for crop health monitoring in order to stop the spread of disease and support efficient management techniques. Implementing biosensors in agricultural settings can help tackle this problem. Biosensors can aid in sustainable agricultural activity by detecting pathogens and pesticides in crops. Farmers may enhance crop production by detecting diseases early with the use of these biosensors. Nanobiosensor-based technology offers nondestructive, minimally intrusive, cost-effective, and user-friendly solutions for detecting plant infections directly. This chapter discusses the way several biosensor types are used in agriculture to monitor a range of plant pathogens, considering the issues that need to be resolved. This chapter also discusses the uses and benefits of the kinds of biosensors, such as electrochemical, optical, and plant wearable technologies, in smart farming.