Cyanobacteria and microalgae represent promising sources for sustainable production of biofertilizers and biostimulants, which can improve crop yield and quality and contribute to food security. However, despite their potential, their exploration remains incomplete, hindered by technical and economic challenges that arise when attempting to scale up production. The primary focus of this review is to delve into the active chemical compounds responsible for the biofertilizing and biostimulating roles of cyanobacteria and microalgae. In addition, it explores the essential unit operations involved in transforming their biomass into potential bioproducts. Moreover, this review highlights studies that have employed cyanobacteria and microalgae as sources of biofertilizer in various crops, describing their mode of action and application. By integrating cyanobacteria and microalgae processing with other advanced biotechnological, the viability of these products for sustainable agriculture can be significantly enhanced.