Abstract CO 2 hydrogenation has attracted great attention, yet the quest for highly-efficient catalysts is driven by the current disadvantages of poor activity, low selectivity, and ambiguous structure-performance relationship. We demonstrate here that C 3 N 4 -supported Cu single atom catalysts with tailored coordination structures, namely, Cu–N 4 and Cu–N 3 , can serve as highly selective and active catalysts for CO 2 hydrogenation at low temperature. The modulation of the coordination structure of Cu single atom is readily realized by simply altering the treatment parameters. Further investigations reveal that Cu–N 4 favors CO 2 hydrogenation to form CH 3 OH via the formate pathway, while Cu–N 3 tends to catalyze CO 2 hydrogenation to produce CO via the reverse water-gas-shift (RWGS) pathway. Significantly, the CH 3 OH productivity and selectivity reach 4.2 mmol g –1 h –1 and 95.5%, respectively, for Cu–N 4 single atom catalyst. We anticipate this work will promote the fundamental researches on the structure-performance relationship of catalysts.