Homologation reactions are of importance in synthetic chemistry. Carbon dioxide can be a valuable C1 building block for homologation reactions as a convenient C1 source, yet the challenges – low reactivity of CO₂ and reversibility of reactions – must be tackled. This chapter summarizes classical examples of homologation reactions of CO₂ and recent advances of CO₂ -functionalization and utilization from the perspective of potential homologation reactions. There are ample opportunities to develop ideal CO₂-utilization by connecting homologative CO₂ -funtionalization and nature's carbon fixation processes – TCA and CBB cycles.