  Sterile neutrinos could provide a link between the Standard Model particles
and a dark sector, besides generating active neutrino masses via the seesaw
mechanism type I. We show that, if dark matter annihilation into sterile
neutrinos determines its observed relic abundance, it is possible to explain
the Galactic Center $\gamma$-ray excess reported by the Fermi-LAT Collaboration
as due to an astrophysical component plus dark matter annihilations. We observe
that sterile neutrino portal to dark matter provides an impressively good fit,
with a p-value of 0.78 in the best fit point, to the Galactic Center
$\gamma$-ray flux, for DM masses in the range (40-80) GeV and sterile neutrino
masses 20 GeV $\lesssim M_N < M_{DM}$. Such values are compatible with the
limits from Fermi-LAT observations of the dwarfs spheroidal galaxies in the
Milky Way halo, which rule out dark matter masses below $\sim$ 50 GeV (90 GeV),
for sterile neutrino masses $M_N \lesssim M_{DM}$ ($M_N \ll M_{DM}$). We also
estimate the impact of AMS-02 anti-proton data on this scenario.
