The design of multimetal catalysts holds immense significance for efficient CO 2 capture and its conversion into economically valuable chemicals. Herein, heterobimetallic catalysts (M i M o )L were exploited for the CO 2 reduction reactions (CO 2 RR) using relativistic density functional theory (DFT). The octadentate Pacman-like polypyrrolic ligand (H 4 L) accommodates two metal ions (Mo, W, Nd, and U) inside (M i ) and outside (M o ) its month, rendering a weak bimetal coupling-assisted MN 4 catalytically active site. Adsorption reactions have access to energetically stable coordination modes of −OCO, −OOC, and −(OCO) 2 , where the donor atom(s) are marked in bold. Among all of the species, (U i Mo o )L releases the most energy. Along CO 2 RR, it favors to produce CO. The high-efficiency CO 2 reduction is attributed to the size matching of U with the ligand mouth and the effective manipulation of the electron density of both ligand and bimetals. The mechanism in which heterobimetals synergetically capture and reduce CO 2 has been postulated. This establishes a reference in elaborating on the complicated heterogeneous catalysis.