In semi-arid regions, the utilization of water with lower quality for irrigation, such as brackish water, is common. However, utilizing these causes negative effects on the absorption and accumulation of nutrients. One strategy for this issue is using tolerant species combined with techniques that reduce the impact of salt stress. In this regard, biostimulants produced from algae extracts could be an alternative for mitigating salt stress in plants. The objective was to evaluate the foliar mineral element content of the ornamental plants Celosia argentea and Catharanthus roseus cultivated under different levels of electrical conductivity of irrigation water and concentrations of biostimulant from algae extract (Ascophyllum nodosum). The experiment was conducted in a protected environment, under a randomized block design, arranged in sub-subdivided plots, with the plots being formed by two levels of ECw (0.5 and 2.5 dS m-1), as subplots by four concentrations of extract of algae (0, 400, 800 and 1200 mg L-1) and the sub-subplots corresponded to two species of ornamental plants (Celosia argentea and Catharanthus roseus). Foliar nitrogen and potassium levels increased with the increase in salinity and biostimulant for the species C. argentea; however, foliar phosphorus, calcium, and magnesium levels decreased with the increase in salinity and biostimulant for both species. In this context, the use of algae extract-based biostimulants at concentrations of 400 to 800 mg L-1 is recommended for the cultivation of C. argentea under saline conditions as an effective strategy to improve the species performance and enable its production in different environments.