With the outbreak and ongoing spread of the COVID-19 pandemic, a wave of post-COVID-19 zeitgeist has emerged worldwide. From the perspective of fashion trends, an increasing number of consumers are demanding higher standards of health, environmental friendliness, and sustainability. Over the past 10 years, the integration of technology in clothing has facilitated continuous updates in both functionality and aesthetics. This article aims to explore the relationship between clothing technology and sustainable fashion in the post-COVID-19 era, seeking to enhance the development and innovation of sustainable fashion through the empowerment of clothing technology. This study conducts extensive research on the literature and online case studies, categorizing empowered sustainable fashion technology design cases into six major categories and four directional themes. It introduces an innovative sustainable fashion design assessment model, PCBS (Product, Customer, Business, Society). Subsequently, the knowledge framework is applied in design practice alongside consumer research to validate the system’s usability. Furthermore, this research synthesizes and summarizes the methods through which fashion technology can support sustainable fashion in the post-pandemic era. Designers and practitioners can reference these insights for more advanced sustainable design initiatives, thereby promoting a lower-carbon and environmentally friendly system that drives global innovation and development in a sustainable society.