The aim of this work was to show how gibberellic acid (GA₃) affects growth, metal biosorption, and the content of essential metabolites (cell number, proteins, monosaccharides, chlorophyll a and b, and total carotenoids) in unicellular green algae Chlorella vulgaris treated with lead (Pb) and cadmium (Cd) during 3 days of culture. Under the influence of 10^-5 M GA₃, algal cells bioaccumulated and bioconcentrated toxic metals from nutrient medium in a dose- and exposure-dependent manner. Moreover, this phytohormone protected C. vulgaris against Pb and Cd stress at a range of low concentrations 10^-7-10^-6 M inducing the increase in cell number and protein, photosynthetic pigment, and monosaccharide content in the culture. However, GA₃ was not able to minimize the harmful effects of the highest dose (10^-4 M) of Cd and Pb, because growth inhibition and reduction in metabolite level was observed. The data suggest that GA₃ plays an important role in the growth and metabolism of microalgae C. vulgaris exposed to heavy metal stress and its adaptation ability to a low-level polluted aquatic environment.