Biostimulants are a broad group of numerous compounds that stimulate plant growth and increase plant resistance to environmental stresses. Pansies are in great demand, so new sustainability strategies for their production are still being sought. This study evaluated the effectiveness of partially hydrolyzed gellan gum (HGG) as a natural biostimulant for the production of high-quality pansy plants. In Experiment 1, the effects of drench concentrations of HGG (0, 25, 50, and 100 mg · dm–3) on morphological and physiological parameters of two pansy cultivars were investigated. In Experiment 2, the objective of study was to determine the effect of HGG on growth, flowering and leaf physiology of pansy grown under increasing sodium chloride (NaCl) concentrations (50 and 200 mM). Our results showed in both cultivars growth-promoting effects of HGG, and 100 mg · dm–3 of HGG was the most effective concentration. The increasing salinity imposed as NaCl negatively affected the growth, flowering, visual appearance, relative chlorophyll content (SPAD), stomatal conductance, and chlorophyll fluorescence (Fv/Fm) of plants. However, HGG pretreatment alleviated the adverse effects of salt stress mainly by reducing the decrease of SPAD, Fv/Fm, flower number and biomass in salt-stressed plants at 200 mM NaCl. Overall results indicated that eco-friendly HGG at the proper dose could be used as a tool to enhance growth, flowering and salt stress tolerance in pansy plants.