<p>Thionins are a class of small, cationic plant peptides with well-documented antimicrobial activity. They play a crucial role in plant defense by destroying the cell membranes of pathogens and triggering immune responses. Due to their broad spectrum of activity and natural origin, thionins are increasingly considered eco-friendly alternatives to conventional chemical pesticides in integrated pest management strategies. This review examines the various biological functions of thionins, their molecular mechanisms of action, and their potential applications in agriculture. Particular attention is paid to current limitations, including peptide stability, specificity, regulatory challenges, and innovative approaches to overcome these, such as encapsulation technologies and targeted delivery systems. In addition, the role of thionins in promoting sustainable agriculture and improving the climate resilience of crops will be discussed. Thionins support ecosystem health and food security by reducing dependence on synthetic agrochemicals. Continued research and interdisciplinary collaboration are essential to close current knowledge gaps and facilitate the path to practical implementation. With strategic innovation, thionins can serve as key tools in the development of robust crop protection systems suitable for a changing climate.</p>