Growing population pressures, increasing global energy demand, and the escalating impacts of climate disruption have intensified concerns over future energy security and environmental stability. Solar-driven CO2 reduction is increasingly recognized as a viable strategy to confront these dual challenges. In this context, photoelectrocatalysis provides a particularly attractive approach, as it merges light harvesting with electrochemical control, enabling efficient solar energy conversion under mild reaction conditions while avoiding the need for extreme temperatures or high applied voltages. This combined strategy holds significant promise for achieving efficient and selective CO2 conversion. The chapter provides an overview of the fundamental principles underlying photocatalytic, electrocatalytic, and photoelectrocatalytic CO2 reduction, emphasizing their distinctive operational characteristics. Different photoelectrocatalytic configurations are described and evaluated in a comparative framework. Particular attention is given to factors that govern performance, such as the interaction between catalysts and reactant molecules, operating conditions, and the physicochemical properties of photoelectrodes. Advances in mechanistic understanding and approaches for enhancing activity including the optimization of light harvesting, suppression of charge recombination, and acceleration of surface reaction dynamics are critically examined. The discussion concludes with an assessment of current limitations and potential future directions for the development of photoelectrocatalytic CO2 reduction technologies.