The members of algae are groups of microscopic or macroscopic organisms with simple internal structures that generally live in oceans, moist soil, rivers, ponds, lakes and coastal areas. They are well demonstrated to be admirable natural bio-reserves of bioactive compounds and act as bio-fertilizers, plant growth promoters, anti-herbicides, bio-stimulators and confer tolerance to biotic and abiotic stresses. In the changing agro-climatic conditions and side effects associated with the use of chemical fertilizers, algae-based extracts form a green sustainable source of nutrients and compounds that can elicit phytostimulatory activities. The incorporation of algae-based extracts in crop health management and increasing yield will have a drastic effect on cultivation practices in a sustainable way. Because the algal extracts have multifunctional bio-inoculants that are of plant origin mimicking plant biology. The objective of this review is to get insight into the nature, type and mode of action of different algal extracts in plant growth promotions. This review noticed that different species of Phaeophyta, Rhodophyta, Chlorophyta and Cyanobacterial extracts have phytostimulatory activities. Of which, Phaeophyta aqueous extracts showed a potent application in plant growth promotion and cyanobacteria species contained high anti-pathogenicity along with biotic and abiotic stress tolerance. Interestingly, Rhodophyta species promoted plant growth by symbiotic association with fungi. Although this review reports the role of algal extracts on phytostimulatory activities, the mechanistic basis for the observed activities needs to be unearthed which forms the future scope of studies.