Manganese (Mn) nitrides are important nitrogen (N) carriers for small‐scale intermittent ammonia (NH₃) synthesis. However, only 3∼8 % of lattice N are converted into NH₃. In this study, the geometric and electronic structures of well‐defined Mn₄N and Mn₂N lattices were altered using transition metal heteroatoms (Cr, Fe, Co, Ni, Mo) to understand the driving force behind lattice N diffusion and extraction. Density Functional Theory (DFT) revealed that the binding of early hydrogenation product (NH) follows a linear relationship with lattice N over a wide range of close‐packed surfaces. But, the binding of NH₂ and NH₃ are more sensitive to the geometric and electronic structures. Further, the chemical bonding can be quantitatively characterized with the covalency derived from Crystal Orbital Hamiltonian Population (COHP). In the Eley Rideal‐Mars van Krevelan pathway, the overall NH₃ formation free energy ( ) and lattice N diffusion barrier ( ) are the respective thermodynamic and kinetic determining factors. Aided by a rate‐determining step (RDS) model, Mn₄N modified with Fe, Co, Ni single‐atom dopants all show enhanced rates for NH₃ formation.