In the course of ecological and floristic studies on the Yamal Peninsula in the Yamalo-Nenets Autonomous District (YaNAO, Russia), we have made new findings that supplement the species composition of the vascular plant flora of the Yamal. The data on 25 species (21 genera and 10 families) of alien vascular plants newly recorded in the peninsula in 2018 are presented. Potentilla heidenreichii Zimm. is recorded for the first time for the flora of Siberia. The herbarium specimens referred to in the article are stored in the Herbarium of the Komarov Botanical Institute (LE). The newly discovered species were found in a large isolation from their main range, and in all kinds of disturbed habitats, namely on wastelands, abandoned and new lawns, in ditches and along roadsides, therefore we regard them as alien (alien or adventive). In Yamal, the use of lawn grass mixtures to anchor sandy roadsides and marginal slopes of gas platforms seems to be an important source of penetration of new alien species. A large number of invasive species have penetrated into Yamal, up to Bovanenkovo and Sabetta, in the last 8–10 years, as evidenced by the absence of these species in the “Flora of the Yamal Peninsula” (Rebristaya, 2013).