New information on the occurrence of two alien decapod crustaceans,Macrobrachium nipponenseandProcambarus virginalis, was summarized for Ukraine. The invasive potential of both species was estimated in the context of local environmental and socio-economic issues. Their history as non-native species is marked by the early use of alien decapods as a natural resource by local residents. Both intentional and unintentional introductions occurred forM. nipponense, while the ornamental trade was an important source of non-nativeP. virginalis. New records ofM. nipponenseandP. virginalisfrom open freshwater habitats in the Odesa and Kharkiv provinces suggest continuing expansion of these decapods. We conducted a molecular phylogenetic analysis ofCOIsequences, which confirmed morphological identifications of invasiveM. nipponense. This reinforces the presumed pathway of this species, including its pathway from China to south-western Ukraine.Procambarus fallaxwas found to be paraphyletic in relation toP. virginalis, which was probably caused by analyzing only one mitochondrial gene, which could be impacted by the recent emergence of the latter species.