The dataset presented in the current study contains information regarding alien vascular plant species found in the Middle Volga Region (South-East of the European part of Russia). The dataset overall includes 413 species belonging to 247 genera and 67 families. The described dataset is based on the data published during floristic studies from 1851 to 2019. The dataset does not include alien vascular plant species that have presently disappeared from the territory of the region. It contains a total of 7,782 records of occurrences, extracted from the Salix system of information and analytics, developed in the Institute of Ecology of the Volga River Basin of the Russian Academy of Sciences. A total of 7,782 records were published on the occurrence of alien vascular plants in the Middle Volga Region. Each entry includes information regarding the place of occurrence of the alien plant species, the year of occurrence, the person who recorded the alien plant and who identified it, status of the species (introduced or invasive), link to the herbarium, which contains the specimen and the literary source. If it were impossible to establish the names of the persons who collected the samples and (or) their identification in the identifiedBy and recordedBy fields, the names of the authors of the publication given in the associatedReferences field were entered. The presented dataset supplements the information on the distribution of alien plant species in the whole European part of Russia and specifies the places of their findings in the Middle Volga Region.