The electrochemical reduction of CO2 (CO2RR) has recently attracted increasing attention for converting intermittent electric energy to chemical energy and reducing CO2 emission. Generally, various products including C1 and C2+ chemicals can be produced through CO2RR, and the selectivities of products are strongly determined by the structures of the active sites. In this work, we demonstrate that a penta-coordinated Fe single atom with N (Fe–N5/C) can serve as an efficient catalyst for CO2RR to syngas with tunable compositions. Detailed characterizations reveal that Fe atoms present as single atoms on a N-doped carbon support derived from the thermal treatment of zeolitic tetrazolate framework (ZTF). Specifically, each Fe single atom coordinates with five N atoms to form a pentahedral structure (Fe–N5). Theoretical calculations indicate that CO* desorption is energetically preferred, while CO2 activation to COOH* is the potential-limiting step for CO2RR on the Fe–N5/C surface, leading to an enhancement in CO2RR and suppression of hydrogen evolution reaction (HER). Consequently, the ratio of H2/CO ranges from 0.15 to 2.8 in the potential range of −0.5–−1.0 V when Fe–N5/C is used as the catalyst for CO2RR in 0.1 M KHCO3. This work reports a penta-coordinated Fe single atom for CO2RR to produce syngas with a tunable H2/CO ratio, which may promote the fundamental research on catalyst design for CO2RR.