The W-boson mass, which was recently measured at Fermilab with an unprecedented precision, suggests the presence of new multiplets beyond the standard model (SM). One of the minimal extensions of the SM is to introduce an additional scalar doublet in which the non-SM scalars can enhance W-boson mass via the loop corrections. On the other hand, with a proper discrete symmetry, the lightest new scalar in the doublet can be stable and play the role of a dark matter particle. We show that the inert two Higgs doublet model can naturally handle the new W-boson mass without violating other constraints and that the preferred dark matter mass is between 54 and 74 GeV. We identify three feasible parameter regions for the thermal relic density: the SA coannihilation, the Higgs resonance, and the SS→WW^{*} annihilation. We find that the first region can be fully tested by the High Luminosity Large Hadron Collider, the second region will be tightly constrained by direct detection experiments, and the third region could yield detectable GeV γ-ray and antiproton signals in the Galaxy that may have been observed by the Fermi Large Area Telescope and the Alpha Magnetic Spectrometer AMS-02 experiment.