The overreliance on synthetic fertilizers, insecticides, and growth regulators in contemporary agriculture has generated significant environmental issues, necessitating the exploration of sustainable and bio-based alternatives. Lignin, a complex aromatic biopolymer prevalent in non-woody agricultural leftovers like rice straw, bamboo, sugarcane bagasse, and tobacco stalks, presents significant promise for diverse agricultural applications. This chapter examines the origins, properties, and diverse applications of non-wood lignin in agriculture, highlighting its function in pesticide delivery systems, slow-release fertilizers, metal-chelating fertilizers, soil amendments, biostimulants, carbon sources for soil microbes, and biodegradable mulch films. The distinctive physicochemical properties—namely hydrophobicity, antioxidant capacity, and functional reactivity—facilitate regulated nutrient release, soil enhancement, augmented plant development, and diminished agrochemical contamination. Moreover, lignin’s biocompatibility and biodegradability render it appropriate for the creation of environmentally friendly agricultural goods. Notwithstanding its potential, obstacles persist owing to lignin’s structural variability, hydrophobicity, and propensity for aggregation, necessitating chemical or nanoscale changes. Future research directions encompass the development of standardized, cost-efficient, and environmentally sustainable extraction and modification procedures to enhance lignin’s efficacy and scalability in sustainable agricultural systems. Utilizing lignin from non-wood biomass is a strategic method for advancing a circular bioeconomy and promoting sustainable farming practices.