The growing world population requires a big increase in farming, but harmful germs remain a major problem. Traditional methods for detecting pathogens have limitations in sensitivity, specificity, and speed. Nano-biosensors are revolutionizing pathogen identification in agriculture with their precision and efficiency. This chapter offers a detailed overview of nano-biosensors, covering their principles, materials, and applications for detecting microbial pathogens. It emphasizes the crucial role of pathogen detection in safeguarding agricultural productivity and food security. The basics of nano-biosensors, including their characteristics and operational principles, are explored in depth. Nano-biosensors are categorized based on design, composition, and intended use, highlighting the role of nanomaterials in enhancing sensor performance. Components like nanoparticles, nanocomposites, nanowires, and nanotubes are examined for their ability to detect pathogens in complex agricultural environments. Biological recognition elements such as antibodies, antigens, enzymes, and nucleic acids are crucial for the accuracy of nano-biosensors in identifying different microbial species. The chapter discusses optical methods, electrochemical techniques, and Surface Plasmon Resonance (SPR) as effective approaches for rapid pathogen identification. Applications of Nano-biosensors in agriculture cover the detection of bacterial, fungal, and viral pathogens. Despite their promise, challenges in adoption, ethical considerations, and environmental impacts are addressed, offering a balanced view. Future trends and innovations in nano-biosensors are highlighted, aiming for more effective and sustainable biosensing solutions in agriculture.