A comprehensive review of microalgae and cyanobacteria-based biostimulants for agricultural use highlights their potential as sustainable alternatives to traditional fertilizers. These biostimulants, derived from microalgae and cyanobacteria, can enhance plant growth, nutrient uptake, stress tolerance, and soil fertility while reducing environmental impact. Despite their promising potential, challenges such as high production costs, limited research, and the need for efficient extraction and formulation methods hinder their widespread adoption. The review discusses the selection of high-potential microalgae strains, cultivation techniques, and extraction methods for biostimulant production. It also explores the mechanisms of action, including nutrient uptake enhancement, stress alleviation, and microbial interactions. The review emphasizes the importance of further research to optimize production processes, improve product stability, and ensure regulatory compliance. Additionally, it highlights the economic and market trends, noting the growing demand for microalgae-based biostimulants in agriculture. The review concludes that while microalgae and cyanobacteria-based biostimulants offer significant benefits, addressing technical, economic, and regulatory challenges is crucial for their successful implementation in sustainable agriculture.A comprehensive review of microalgae and cyanobacteria-based biostimulants for agricultural use highlights their potential as sustainable alternatives to traditional fertilizers. These biostimulants, derived from microalgae and cyanobacteria, can enhance plant growth, nutrient uptake, stress tolerance, and soil fertility while reducing environmental impact. Despite their promising potential, challenges such as high production costs, limited research, and the need for efficient extraction and formulation methods hinder their widespread adoption. The review discusses the selection of high-potential microalgae strains, cultivation techniques, and extraction methods for biostimulant production. It also explores the mechanisms of action, including nutrient uptake enhancement, stress alleviation, and microbial interactions. The review emphasizes the importance of further research to optimize production processes, improve product stability, and ensure regulatory compliance. Additionally, it highlights the economic and market trends, noting the growing demand for microalgae-based biostimulants in agriculture. The review concludes that while microalgae and cyanobacteria-based biostimulants offer significant benefits, addressing technical, economic, and regulatory challenges is crucial for their successful implementation in sustainable agriculture.