The study area of this work comprises the subsurface of the Austral-Magallanes basin at a regional scale, including parts of Southern Argentina and Chile territories, and the neighboring offshore. For many years, this basin has been studied as if there were three different independent basins. This paper is a first approach to the understanding of this basin as one single basin, based mainly on subsurface data, including seismic information (3D and 2D), and biostratigraphic ages from wells. For the sake of a better visualization, four regional seismic sections were defined, showing the correlation between the stratigraphic surfaces used in both countries and different domains of the basin. As a result, 12 chronostratigraphic surfaces were regionally interpreted in all the sections, allowing a cross-basin identification of the main geological events and paleoenvironmental evolution.