Abstract: Background and Objective: Green technology has been used to generate bio-fertilizers in the most environmentally friendly way possible. The objective of this study was to study the effect of foliar application of algal extracts as bio-stimulants for improved groundnut growth and seed yield parameters. Materials and Methods: During the two growing summer seasons of 2019 and 2020, two field experiments were conducted in South Tahrir Province, El-Beheira Governorate, Egypt to investigate the impact of foliar spraying with fresh and dried green algae extracts on groundnut (Arachis hypogaea L.). A complete randomized block design with three replications was utilized, with foliar sprays of fresh green algae (1, 2, 3 and 4 g L–1), dried green algae (1, 2, 3 and 4 g L–1) and control (spray with water). Results: All foliar sprays with algal extracts significantly boosted all of the examined parameters. The use of fresh green algae significantly improved plant vegetative growth characteristics, chlorophyll, N, P and K content of leaves and seed production quantity and quality. Fresh green algae treatment with 2 g L–1 surpassed other treatments in seed yield, pod yield and oil yield. The percentage of increase over control treatment are 60.6, 62.4 and 74.5% in seed, pod and oil yield per fed, respectively. Conclusion: It can be concluded that this study pays attention to using green algae extracts as bio-stimulant due to the presence of some plant growth-stimulating compounds and their nitrogen, phosphorus and potash content. Foliar application of fresh green algae proved to improve the growth, yield and oil content of groundnut.