The Putumayo Basin Foothills corresponds to the northwestern corner of the Marañon-OrientePutumayo Megabasin (MOP) shared by Colombia, Ecuador and Perú. The area holds one of the giant fields in Colombia (the Orito Field with 1.5 billion barrels of oil in place) and has a complex structural history that challenges the exploration efforts. This study presents a structural model carried out over a zone in the Putumayo Basin foothills, integrating surface geology, 2D seismic and subsurface data from the Unicornio-1 well. The main purpose was to test new ideas related to the tectonic evolution of the Andean deformation front and its implications in the tectono-stratigraphic history and the petroleum systems involved. The interpreted model also provides an example of a deformation pattern that can be extrapolated to the whole leading edge of the western boundary of the Putumayo Basin. Features like single fault planes with normal and reverse displacement, stratigraphic thickening in some sequences at the hanging walls of faulted blocks, growing-strata anticlines, pop-up structures, shortcut thrust faults and juxtaposition of structures, allow to make a complete interpretation of the structural setting. Four main tectonic events and therefore four tectono-stratigraphic sequences were recognized as follow: (1) a Triassic to Upper Cretaceous extensional phase characterized by horst and graben systems and the accumulation of pre-extensional (Paleozoic to Lower Triassic) and syn-extensional (Upper Triassic to Upper Cretaceous) depositional sequences, (2) a Lower Eocene Pre-Andean Orogeny, with incipient fault inversion processes resulting in a subtle structural relief responsible for the onset of hydrocarbon trap generation and the deposition of post-extensional (Paleocene) and syn-inversion (Eocene to present) sedimentary sequences, (3) a Upper Oligocene to Upper Miocene deformation event (main Andean Orogeny) with intense tectonic inversion evidenced by strong mountain building and the propagation of new thrust faults that triggers a second episode of hydrocarbon trap generation, and (4) a Pliocene (~3Ma) late Andean deformation event causing a transpression regime evidenced by dextral strike-slip displacement clearly identified on surface structures.