Pathogenic plant microorganisms cause significant yield and economic losses in the agricultural sector. Plant diseases are caused by numerous pathogenic microbes, namely, fungi, bacteria, viruses, phytoplasmas, and nematodes. Sustaining maximum productivity requires rapid and early detection of diseases to avoid their spread and minimize associated productivity losses. Although chemical control is used to manage various diseases, it also has adverse effects on the environment and poses a heavy financial burden on farmers. Hence, early detection of diseases is considered the best approach for disease management and prevention. Conventional pathogen detection methods often involve methods based on microscopic visualization or techniques such as enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR). These methods are time-consuming and require specialized instruments/lab setups; hence, they are not considered suitable for in situ detection. In recent years, immunosensors have presented promising alternatives for pathogen detection. In this chapter, we present a possible application of immunosensors for plant pathogen detection, with various examples showing their efficiency. Improved and accurate plant pathogen detection by immunosensors can be used in integrated disease management.