Fossil fuel-based hydrocarbon economy has invoked a serious climate change due to ever-increasing emission of CO₂. In this regard, electrosynthesis has emerged as a promising route that enables the clean and continuous production of chemicals and fuels.^[1] Electrochemical production of hydrogen peroxide (H₂O₂) via the two-electron (2e⁻) oxygen reduction reaction (ORR) can serve as a promising alternative for the currently prevailing anthraquinone process [1,2]. However, improving H₂O₂ selectivity remains one of important challenges in electrochemical H₂O₂ production because 2e⁻ ORR competes with 4e⁻ ORR, further reduction of H₂O₂ (2e⁻+2e⁻ ORR), and H₂O₂ chemical disproportionation. Carbon nanomaterials have demonstrated promising performance for H₂O₂ production as low-cost electrocatalysts [3–5], however understanding of key structural factors and active sites is still lacking. In this work, we have prepared nanoporous carbon-based model catalysts and conducted a systematic study to identify the active oxygen functionality and carbon structure factor [6]. We have found that the carboxyl (O−C=O) groups located at the graphitic edge carbons are the major active sites for the electrosynthesis of H₂O₂ (Figure (a)). The best-performing carbon catalyst (O-GOMC-5.5) with abundant active oxygenated graphitic edge carbons exhibited the highest H₂O₂ production activity among the reported carbon-based catalysts (Figure (b)) and excellent long-term stability (168 h) with almost 100% of H₂O₂ faradaic efficiency.