Integration of half-metallic materials and 2D spacers into vertical magnetoresistive spin valves may pave the way for effective low-power consumption storage and memory technologies. Driven by the recent successful growth of graphene/ half-metallic Co 2 Fe(Ge 1/2 Ga 1/2 ) (CFGG) heterostructure, here we report a theoretical investigation of magnetic tunnel junction (MTJ) based on the ferromagnetic CFGG Heusler alloy and the MoS 2 spacer of different thicknesses. Using ab initio approach, we demonstrate that the inherent ferromagnetism of CFGG is preserved at the interface, while its half-metallicity is recovering within few atomic layers. Ballistic transport in CFGG/ MoS 2 /CFGG MTJ is studied within the nonequilibrium Green's function formalism, and a large magnetoresistance value up to ∼10 5 % is observed. These findings support the idea of effective spintronics devices based on half-metallic Heusler alloys and highly diversified transition metal dichalcogenide family.