The invasive alien bivalve species Sinanodonta woodiana has been reported for the first time from the Republic of Moldova in 2003. In the study period 2008–2017, this species was recorded at six sampling stations in the Prut River basin: Leova, Goteşti, Cahul, Lake Manta, Lake Beleu, and Cîşliţa-Prut, which basin part belongs to the Wetland Danube River Area of international importance. The most numerous size group was represented by specimens with a shell length of 8–12 cm. The highest density of S. woodiana was 40 ind./m², while the highest biomass was 750 g/m². The largest measured shell had a length of 240 mm. The smallest mature specimen had a shell length of 55 mm. Our results show that this mussel species has successfully established population in the R. Moldova, spreading upstream in the Prut River basin with estimated rate of 15 km per year. We discuss certain competitive advantages of S. woodiana, such as phenotypic plasticity, regeneration capacity, early maturation, high density and biomass, and tolerance to a wide range of environmental factors, which may pose a high risk to the native unionid bivalves in the Lower Prut River basin.