Cyanobacteria are bioactive photosynthetic prokaryotes that have a superior ability to fix atmospheric nitrogen and are highly competitive in the microflora community. They also improve the physical and chemical properties of the soil and increase its water-holding capacity. Therefore, cyanobacteria are used as biofertilizers in agriculture. Cyanobacteria are able to promote plant growth by providing nutrients and producing many highly effective chemical compounds, such as enzymes and hormones, in the plant rhizosphere, giving the plant a highly competitive ability. In addition to activating plant defense responses against soil-borne pathogens, they have an effective strategy as a biocide against bacteria, fungi, and nematodes that attack plants. With multiple beneficial biological roles, the environmentally friendly cyanobacteria occupied the role of the maestro in sustainable agriculture.