Abstract: Photoelectrocatalysis is a sustainable process that plays a central role in clean energy production and pollution removal. Due to the constraints of current photoelectrocatalysts such as instability and scarcity, scientists have resorted to carbon nanomaterials that are more stable and abundant. It has been found that γ-graphdiyne (GDY), the most stable carbon phase among graphynes that contains a diacetylene bond, has some striking properties such as well-ordered pores, non-uniform electronic structure, easily tunable bandgap and excellent photoelectric performance. It has become a new “star” as a highly active photoelectrocatalyst. Its properties, synthesis strategies and photoelectrocatalytic applications are reviewed. Five reaction systems are summarized based on the phase state of the precursors and catalysts, which include liquid-solid, liquid-liquid, gas-liquid, gas-solid, and solid-gas systems. The roles GDY play in photoelectrocatalysis itself, or as a support for single atom catalytic species are discussed. Problems for current research work are discussed and future research trends are proposed.