The dataset summarizes information on vascular plants occurrences in mesophytic pine forests in the upper Ob region (South Siberia). The dataset consists of 8954 occurrence records. The records are extracted from geobotanical relevés which were made during field explorations of the territory in 2003-2021. A total of 300 species belonging to 193 genera and 61 families are reported. The work is under the support of № FSUS-2021-0012 "Ecosystems of pine and birch forests as regulators of nitrogen and carbon balance in the forest landscape of Western Siberia", corresponds to the theme of the Central Siberian Botanical Garden SB RAS AAAA21-121011290026-9 "Vegetation of Northern Asia: diversity, ecological and geographical patterns of formation, functioning of populations".