Climate change is intensifying abiotic stresses such as drought, salinity, heat, and oxidative stress, which negatively impact agricultural productivity and threaten food security. Cyanobacteria, or blue-green algae, are photosynthetic microorganisms that thrive in extreme environments and exhibit resilience to these stresses. This chapter explores the mechanisms through which cyanobacteria alleviate abiotic stress in plants and their potential agricultural applications. Cyanobacteria enhance drought tolerance by producing extracellular polysaccharides that retain soil water and phytohormones such as auxins and gibberellins that promote plant growth under water-limited conditions. Their nitrogen-fixing ability improves soil fertility, particularly in nutrient-depleted soils under stress. Cyanobacteria also help plants tolerate salinity by reducing ion toxicity, stabilizing cellular structures, and promoting growth. Furthermore, they possess heat-shock proteins and antioxidants that protect plants from oxidative damage caused by heat stress. Continued research is needed to unlock the full potential of cyanobacteria as a sustainable solution for mitigating climate change-induced abiotic stress and ensuring resilient agricultural systems for sustained crop production.