Heteroatom-doped carbon materials with superior physico-chemical properties and high stability are potential candidates for environmentally friendly metal-free catalysis. In this study, mesoporous carbon materials with high N content and lattice defects were successfully fabricated via self-templated carbonization of a two-dimensional covalent organic framework (2D COF). The ordered structure and clear composition of intrinsic COF precursors aid the understanding of the specific role of dopants in the as-prepared N-doped mesoporous carbon materials. Based on the obtained experimental results and characterizations, graphitic N and its related defects were found to be closely associated with catalytic activity, indicating they are probably the main active sites. In addition, the obtained catalyst showed remarkable catalytic performance in both hydrogenation of nitroarenes and Knoevenagel condensation of aromatic aldehyde derivatives in aqueous solution. This study is expected to provide a new inspiration for the synthesis of heteroatom-doped carbon materials from cost-effective COFs via self-templated carbonization for eco-friendly metal-free catalysis.