The Golfo San Jorge Basin () is a hydrocarbon-rich sedimentary basin located in eastern Patagonia, Argentina. The basin covers the entire San Jorge Gulf and an inland area west of it, having one half located in Santa Cruz Province and the other in Chubut Province. The northern boundary of the basin is the North Patagonian Massif while the Deseado Massif forms the southern boundary of the basin. The basin has largely developed under condition of extensional tectonics, including rifting.
The basin is of paleontological significance as it hosts six out of 22 defining formations for the SALMA classification, the geochronology for the Cenozoic used in South America.
At the center of the basin accumulated sediments reach more than of thickness. Oil was first discovered in 1907 and over the years it has become the second most productive hydrocarbon basin in Argentina after Neuquén Basin.
The stratigraphy of the Golfo San Jorge Basin covers the following units: