Reactions of nickel complexes supported by an anionic PNP pincer ligand (PNP^– = N[2-PⁱPr₂-4-Me-C₆H₃]₂) toward CO₂ and CO are investigated, particularly for interrogating their C–O bond formation/cleavage chemistry. The formation of a nickel formate species (2) was accomplished by the reaction of (PNP)NiH with CO₂, while the structural isomer complex (PNP)NiCOOH-κC (4) was successfully produced from the corresponding nickel hydroxyl compound by exposing it to CO(g). Its structurally unique character was gleaned by obtaining two solid-state structures for (PNP)NiCOOH-κC (4) and {(PNP)Ni}₂-μ-CO₂-κ²C,O (6); the latter was obtained from the reaction of 4 with a nickel hydroxyl complex. Both species possess a NiCOO-κC binding mode, which is reminiscent of the binding mode found at the carbon monoxide dehydrogenase (CODH) active site with its Ni–COO–Fe fragment. The cationic species {(PNP)NiCO}⁺ (7) was also prepared via the protonation of 4, which then led to the investigation of the C–O bond formation in 7 by adding a nucleophile such as OH^–.