This study aimed to evaluate the effects of salinity stress and the application of marine algal extracts on Chrysanthemum morifolium. The experiment was conducted in a factorial arrangement based on a completely randomized design (CRD) with three replications. Treatments included foliar application of two algal extracts brown algae (Polycladia indica) and spirulina (Arthrospira platensis) as well as a non-treated control, combined with three salinity levels (0, 4, and 8 dS/m). Measured parameters comprised plant height, number of leaves, buds, and flowers, fresh and dry shoot weight, total phenolic content, chlorophyll concentration, proline accumulation, electrolyte leakage, peroxidase activity, petal anthocyanin, and total antioxidant capacity. Analysis of variance indicated that the interaction between algal treatment and salinity stress significantly affected the number of leaves, buds, and flowers, electrolyte leakage, total phenol, and anthocyanin content at the 1% significance level. Application of algal extracts, especially spirulina, significantly enhanced several morphophysiological traits under both saline and non-saline conditions. Elevated salinity reduced chlorophyll content; however, algae application effectively mitigated this decline. The highest mean number of flowers (134) and buds (22) was recorded in the spirulina treatment under non-saline conditions, while the lowest (43.33 and 4.55, respectively) occurred under 8 dS/m salinity without algae. Additionally, the highest proline concentration (0.75 µmol/g FW) was observed in the spirulina-treated plants, whereas the lowest was noted in the control group. Overall, the use of marine algal extracts can be considered a promising biostimulant strategy for improving growth performance and enhancing tolerance to salinity stress in Chrysanthemum morifolium cultivation