Insular ecosystems are sensitive to alien invasive species. The Balearic Islands have been colonized by a large list of invasive species, in most cases due to human activity. White-toothed shrews have been historically recorded in this archipelago and to date four different species have been found. In this study we focus on the white-toothed pygmy shrew (Suncus etruscus) at the island of Mallorca, assessing its current status and identifying both its genetic variation and geographic structure. During the last 50 years this species has colonized a large proportion of the island. Haplotype network analyses support the hypothesis of a unique and recent colonization event from a single but unknown source population. Available genetic information suggests the populations from northeast Iberian Peninsula (Catalonia) and southwest France (Camarge) as the most plausible source of the lineage found in Mallorca. The recent and extensive distribution of Suncus etruscus on this island is characteristic of a fast growing population at an invasive colonization phase, indicating that it has found in Mallorca suitable ecological conditions to thrive.