This article reviews all available information on the species composition, current distribution, and origins of the neobiotic (non-indigenous and restoring the lost range) freshwater mollusks in Siberia. (2) An extensive literary search has been carried out, and virtually all existing publications of recent decades on the findings of freshwater mollusk species new to Siberia were taken into account. We examined extensive malacological collections of some of Russia’s and Kazakhstan’s scientific organizations. The core of the examined material is our own observations and collections made in various parts of Siberia and adjacent areas. (3) An annotated checklist of neobiotic species of mollusks reliably recorded in Siberia is presented, and probable mechanisms and “corridors” of infiltration of these species into the region are discussed. Most of the discovered snail species belong to a group popular among aquarists, and their source of introduction is obvious. Another large portion of species infiltrate into the region with the development of fish farming. A classification of species of neobiotic freshwater mollusks of Siberia was proposed and a forecast was made for changes in the Siberian freshwater malacofauna for the coming decades. (4) In our opinion, at present it is possible to accept the newest stage in the genesis of the freshwater malacofauna of Siberia, occurring in conditions specific to the Anthropocene.