The graphene-based room-temperature chemiresistive gas sensors have low sensitivity (especially for ppb-level organophosphorous compounds, OPCs), limiting their practical applications. Herein, a novel coupling single-atom Cu and N-enriched, π-conjugated carbon nanodots (NCDs) strategy is proposed to synthesize graphene-based sensing materials with excellent room-temperature DMMP sensing performances. Taking rGO-NCDs-Cu as the example, the N-enriched structures facilitate the adsorption of DMMP by providing more active sites and strengthening the hydrogen bonding interactions between -NH 2 and DMMP molecules. The π-conjugated structures can construct large π-delocalization network promoting charge generation and transport. The N-enriched and π-conjugated structures also result in narrowing band gap of NCDs, effectively enabling the increase of carrier transfer rate. Moreover, the introduction of single-atom Cu sites with Cu-N 2Cl 2 structure further strengthens the hydrogen bonding interactions between sensing materials and DMMP molecules. Benefiting from this novel coupling strategy, rGO-NCDs-Cu sensor shows high response value of 13.95 % towards 340 ppb DMMP at room temperature. Meanwhile, rGO-NCDs-Cu sensor exhibits short response time (77 s) and recovery time (198 s), low practical limit of detection (34 ppb), excellent repeatability and high selectivity. Our work offers a new strategy for rational design of graphene-based materials for detection of OPCs at room temperature.