In recent years, photocatalysis (PC) and photoelectrocatalysis (PEC) technologies have shown great promise as low-cost, environmentally friendly, and sustainable strategies in addressing the issues of energy shortages and environmental pollution, which has become a research hotspot. Titanium dioxide (TiO2)-based PC and PEC are the most promising sustainable technologies for advanced oxidation applications. Due to its inherent characteristics, including high oxidation ability, low price, and stability, TiO2 photocatalyst has been widely studied and used in different scales for numerous decades. For practical applications in these areas, the engineering of the photocatalysts and the design of the PC and PEC devices must be both environmentally and economically sustainable. On the one hand, for the engineering of the photocatalysts, the photocatalyst shall be able to deliver the following characteristics, including large specific surface area, high absorption of light, rapid and low-cost separation and regeneration, and high stability. On the other hand, the design of the PC and PEC devices shall facilitate high in energy utilization and catalytic efficiency, and low in building and operational cost. This work covers the reaction mechanism of TiO2-based PC and PEC technologies, sustainable design, and preparation of TiO2 photocatalysts as well as sustainable design in PC and PEC devices for wastewater treatment, sensing, and water splitting. Finally, we provide some critical perspectives on the future development of TiO2-based PC and PEC technology.