The use of carbon-based materials is an appealing strategy to solve the issue of excessive CO emissions. In particular, metal-free nitrogen-doped carbon materials (mf-NCs) have the advantages of convenient synthesis, cost-effectiveness, and high conductivity and are ideal electrocatalysts for the CO reduction reaction (CORR). However, the unclear identification of the active N sites and the low intrinsic activity of mf-NCs hinder the further development of high-performance CORR electrocatalysts. Achieving precise control over the synthesis of mf-NC catalysts with well-defined active N-species sites is still challenging. To this end, we adopted a facile synthesis method to construct a set of mf-NCs as robust catalysts for CORR. The resulting best-performing catalyst obtained a Faradaic efficiency of CO of approximately 90% at −0.55 V (vs. reversible hydrogen electrode) and good stability. The electrocatalytic performance and in situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy measurements collectively revealed that graphitic and pyridinic N can synergistically adsorb CO and HO and thus promote CO activation and protonation.