Reservoirs formed in the process of human activity are a new type of reservoir and an integral element of landscapes. Studies of these water bodies make it possible to establish the mechanisms of formation and functioning of phytoplankton in artificially created ecosystems. Studies were conducted in 2018-2020 on phytoplankton assemblages in ponds of the Central Polissia area in Ukraine. The work aimed to evaluate the water quality of the Central Polissia ponds according to structural and functional indicators of phytoplankton development. Differences in phytoplankton abundance, biomass, and structure, dominant complexes of species were assessed in the studied ponds. 103 species of algae, represented by 105 intraspecific taxa, including those containing the nomenclature type species, from 7 divisions, 11 classes, 20 orders, 31 families, and 60 genera were found in the studied ponds. The occurrence of 9 types of algae, which were not previously found in the territory of Ukrainian Polyassia. Chlorophyta, Euglenozoa, and Miozoa were the structure- forming divisions in the phytoplankton biomass in the studied ponds. The dominant species complex of the ponds’ phytoplankton (according to abundance and biomass) was formed by 5–18 species, which accounted for 33–62% of the species richness of the water bodies. Shannon’s diversity index indicated the predominance of the polydominant structure of phytoplankton in most ponds. Phytoplankton assemblages of the studied ponds in central Polissia were characterized by high biodiversity, differentiated structure, and differences in dominant species, which highlight the critical role of artificial water bodies in biodiversity. This study provides necessary information for understanding the changes in the phytoplankton community caused by anthropogenic impacts on artificial water bodies.