In this work we use syntectonic remagnetization data to determine the synrift geometry of inverted basins. This methodology analyzes remagnetization directions in order to obtain the tilting of beds at the moment of the acquisition of the overprint, filtering the subsequent compressional deformation. We collected samples from Jurassic and Lower Cretaceous limestones and red beds (Cabuérniga and Pas Groups) in the Cabuérniga basin, one of the most important Mesozoic basins developed near the Iberia-Europe Mesozoic plate boundary in northern Spain, that later inverted during the uplift of the Pyrenees. These deposits represent the synrift sequence linked to a widespread extensional stage in the Iberian basins during the Mesozoic. All sampled rocks show a normal polarity remagnetization. Fold and conglomerate tests indicate that remagnetization postdates the main extensional stage of basin formation (Late Jurassic−Barremian) and was acquired before the subsequent compressional deformation. The analysis of these overprinted directions allows the basin geometry of the studied area to be restored at the moment of acquisition of the remagnetization. This approach represents a powerful tool to study basinal evolution and uplift of sedimentary basins, to be tested in other inverted basins with syn-extensional related secondary overprints.