Excessive greenhouse gas (GHG) emissions arising from nonrenewable fossil fuel utilization are causing serious climate change. Since carbon dioxide (CO 2 ) contributes about 76% of GHGs in the atmosphere, utilization of CO 2 could reduce its negative impact on the environment. Among the technologies available for CO 2 conversion, photocatalytic (PC) and photoelectrocatalytic (PEC) reduction of CO 2 into valuable solar fuels have made significant progress. These two technologies are environmentally friendly and effective in concurrently solving energy crises. Insights on the principles, thermodynamics, and limitations of photocatalysis/photoelectrocatalysis using sustainable energy for reducing CO 2 are elucidated in this review. The configurations of cathode−anode and the proton exchange membrane in PEC membrane reactors are discussed. The advances of photoelectrocatalysts such as titania, copper oxides, complex metal−organic frameworks (MOFs), membrane-based immobilized, and metallic photoelectrocatalysts for PEC reduction of CO 2 are also incorporated. Discussion of possible reaction mechanisms using DFT simulation to postulate feasible pathways occurring on catalyst surfaces is presented. It is recognized that PEC CO 2 reduction is critical in the utilization of CO 2 and solar energy research. It is also deduced that advances in reactor configurations along with photoelectrocatalyst materials are vital in mitigating excess CO 2 emissions to generate solar fuels.