Background: Seaweed-derived extracts have gained popularity in agriculture as bioproducts with phytostimulatory effects on plant growth and development. Methods: This study assessed the effect of polysaccharide-enriched extracts (PEEs) derived from six Moroccan seaweeds on tomato growth, yield, and fruit quality. PPEs were applied to tomato plants as soil drench in a greenhouse experiment. Growth parameters including plant height (cm) and number of leaves, flowers, and flower buds were recorded every 15 days. Yield and quality parameters of the harvested fruits were also recorded after each harvest. Results: The obtained results showed that all PEEs improved the growth, yield, and fruit quality of treated tomato plants. According to principal component analysis, the presence of SO₄, galactose, glucose, and maltose in the characterized polysaccharides was closely associated with their effect on plant growth, yield, and fruit quality parameters. Conclusions: PEEs obtained from Gelidium crinale,Schizymenia dubyi, Fucus spiralis, and Bifurcaria bifurcata exhibited the highest biostimulant effects and could be used as bioproducts for improved tomato yield and fruit nutritional quality.