We perform the first-principles simulation on the interfacial electronic structures and magnetic properties of Fe4N(001)/Si and Fe4N(111)/graphene bilayers. For Fe4N/Si bilayers, the strong interfacial bonding reduces the Fe4N magnetic moment, but induces the spin polarization in Si with a magnetic moment of −0.06μВ for Si located at the bottom of interfacial FeI atom. For Fe4N/graphene bilayers, the interfacial bonding is so weak that the reduced Fe4N magnetic moment only comes from the compressive strain modulation due to the large lattice mismatch. The observed p-type doping of graphene is induced by a larger work function of Fe4N(111) surface than that of graphene. Our results demonstrate that the interfacial bonding between Fe4N and Si/graphene plays a significant role in manipulating their electronic properties.