We introduce a simple scenario involving fermionic dark matter ($chi$) and singlet scalar mediators that may account for the Galactic Center GeV $gamma$-ray excess while satisfying present direct detection constraints. CP-violation in the scalar potential leads to mixing between the Standard Model Higgs boson and the scalar singlet, resulting in three scalars $h_{1,2,3}$ of indefinite CP-transformation properties. This mixing enables s-wave $chi{barchi}$ annihilation into di-scalar states, followed by decays into four fermion final states. The observed $gamma$-ray spectrum can be fitted while respecting present direct detection bounds and Higgs boson properties for $m_{chi} = 60 sim 80 $ GeV, and $m_{h_3} sim m_{chi}$. Searches for the Higgs exotic decay channel $h_1 to h_3 h_3$ at the 14 TeV LHC should be able to further probe the parameter region favored by the $gamma$-ray excess.
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