The present study reports six new and consecutive records of the Atlantic blue crab (Callinectes sapidus Rathbun, 1896) in the southern coast of Portugal. Specimens were caught during less than two months (22nd November 2018 – 18th January 2019) as bycatch of trammel nets operated by small-scale fishing boats in scattered locations along the Algarve coast and in the Ria Formosa lagoon. Four adult males (221–236 mm carapace width) and two adult females (191–207 mm carapace width) were caught at relatively shallow depths (1–6 m), on muddy and sandy bottoms in the Ria Formosa lagoon and in the Algarve coast. Morphometric parameters of the specimens are compiled and the respective occurrences are mapped for biogeographic purposes. These first three occurrences in the Algarve coast and the second, third and fourth records in the Ria Formosa lagoon, further supported by additional anecdotal evidences and recent sales at the wholesale market, reveal a rapid westward expansion and confirm the establishment of C. sapidus along the southern coast of Portugal. Possible sources of introduction and causes for the distributional expansion are evaluated. The potential impacts of this invasive species on local ecosystems and fishing/harvesting resources are discussed.