In the global context of nuclear energy renaissance and green development, the issue of tritium emissions has garnered significant attention. Reducing tritium emissions is a crucial measure for enhancing the environmental and public acceptance of nuclear energy. However, there is currently a lack of comprehensive and objective analysis of tritiated water purification technologies from the perspective of nuclear energy applications, and the overall technical routes and processes remain unclear. Moreover, given the rapid advancements in this field, existing literature reviews are in urgent need of updates. This review begins by outlining the generation scenarios, characteristics, and regulations of tritiated water in the nuclear energy field, highlighting the pressing demand for tritiated water purification technologies in nuclear power plant, spent fuel reprocessing plant, and future nuclear fusion facilities, in particular, inland nuclear facilities have higher requirements for tritium purification, with typical concentration of tritiated water to be purified ranging from 107 to 1012 Bq/L. Subsequently, the work reviews latest research progress in three mainstream tritiated water purification technologies—water distillation (WD), combined electrolysis and catalytic exchange (CECE), and liquid phase catalytic exchange (LPCE). It identifies the exploration and establishment of tritiated water purification mechanism and key physicochemical parameters, the industrial-scale preparation of efficient hydrogen-water isotope exchange catalysts, and the adaptive modification of electrolytic systems as the current research priorities and challenges. Building on this foundation, this work concludes four feasible tritium purification routes from the perspective of application: WD+storage/electrolysis+cryogenic distillation (CD) route, the CECE+storage/CD route, WD+CECE+storage/CD route, and the LPCE+CD route. It provides a comprehensive analysis of their treatment capabilities, applicable conditions, advantages, and disadvantages, aiming to offer references for tritiated water purification technology and engineering construction.