In the growing field of nanoelectronics, spin filtering devices are a topic of great interest. In recent years, there have been major advances in the synthesis of slim zigzag graphene nanoribbons (ZGNRs) that show inherent spin polarization along the edges, suggesting their potential as spintronic devices. In the following contribution, we show through theoretical investigations how a nitrogen doping pattern that is used to stabilize longer ZGNRs may turn a 2-ZGNR into an efficient spin filtering device through either simple physical or chemical transformations. Modeling of the electronic structure is performed using density functional theory, and we access global and local transport properties in the quasi-stationary limit from nonequilibrium Green’s function simulations. Our work shows that both negative gating and double protonation change the nature of the ground state of these systems, which enables efficient spin-selective transport.