Onshore and offshore geological and geophysical observations and numerical modeling have greatly improved the conceptual understanding of magma‐poor rifted margins. However, critical questions remain concerning the thermal evolution of the prerift to synrift phases of thinning ending with the formation of hyperextended crust and mantle exhumation. In the western Pyrenees, the Mauléon Basin preserves the structural and stratigraphic record of Cretaceous extension, exhumation, and sedimentation of the proximal‐to‐distal margin development. Pyrenean shortening uplifted basement and overlying sedimentary basins without pervasive shortening or reheating, making the Mauléon Basin an ideal locality to study the temporal and thermal evolution of magma‐poor hyperextended rift systems through coupling bedrock and detrital zircon (U‐Th)/He thermochronometric data from transects characterizing different structural rifting domains. These new data indicate that the basin was heated during early rifting to >180°C with geothermal gradients of ~80–100°C/km. The proximal margin recorded rift‐related exhumation/cooling at circa 98 Ma, whereas the distal margin remained >180°C until the onset of Paleocene Pyrenean shortening. Lithospheric‐scale numerical modeling shows that high geothermal gradients, >80°C/km, and synrift sediments >180°C, can be reached early in rift evolution via heat advection by lithospheric depth‐dependent thinning and blanketing caused by the lower thermal conductivity of synrift sediments. Mauléon Basin thermochronometric data and numerical modeling illustrate that reheating of basement and synrift strata might play an important role and should be considered in the future development of conceptual and numerical models for hyperextended magma‐poor continental rifted margins. Key Points Recorded synrift exhumation and basin heating of the proximal rift to >180°C with geothermal gradients of ~80°C/km Synrift heating of distal rift reached >180°C and persisted until exhumation at circa 50 Ma due to Pyrenean inversion Thermal evolution of magma‐poor hyperextended continental rifts is not predicted by classic pure‐shear model due to depth‐dependent thinning