Structural analysis through precise digital mapping combined with microstructural and quantitative finite strain data were used to investigate strain partitioning and strain shape evolution during the late-stage oblique tectonic collapse of a hot orogen. The Tanneron massif in SE France was structured in an oblique tectonic regime at the end of the Variscan orogeny, leading to the exhumation of lower to middle crustal migmatite terrains. Strain patterns show prominent stretching lineations associated with L>S tectonites and dextral strike-slip SZ compatible with subsimple shear deformation. The overall kinematic with pure shear sub-horizontal constrictional flow and sub-vertical simple shear-dominated transcurrent corridors depict a transtensional regime. The progressive transtensional deformation evolves through two successive phases, the first characterised by a dominant sub-horizontal flow of the ductile crust represented by gently dipping foliation and widespread sub-horizontal stretching lineations followed by a second plane strain flow associated with vertical foliation and S-L tectonites. Finite strain analysis confirms the monotony of the L>S and S-L tectonites and highlights a lithological control on the finite strain ellipsoid shape with meta-igneous units defining L>S fabrics while meta-sedimentary units depict S-L fabrics. Microstructural observations also constrain the temperature evolution of the progressive transtensional deformation. Sub-horizontal flow starts at supra-solidus conditions and progresses to sub-vertical shear down to greenschist facies solely in hydrated meta-sedimentary units. We propose a rheologically driven strain path partitioning during the progressive exhumation of this deep crust during a two-phase transtensional regime.