Sustainable fashion refers to textile materials and processes that are environmentally friendly. To achieve sustainable fashion, it is ensured that entire value chains, including design, manufacturing, distribution, and utilization, adhere to the principles of resource efficiency, pollution prevention, and circularity. Sustainable fashion certification plays a crucial role by codifying criteria for efficient resource use, waste reduction, and the adoption of eco-friendly materials. These efforts lower the carbon footprint and conserve natural resources. Therefore, certification and standardization serve as essential tools for evaluating a product's environmental sustainability, commercial viability, and overall contribution to sustainable fashion. Additionally, transparent certification and harmonized standards strengthen consumer trust in certified products and the systems that produce them. This chapter reviews standards, certifications, production challenges, illustrative case studies, emerging trends, and materials-focused approaches to sustainable textile manufacturing. The discussion is intentionally integrative. It moves from principles to instruments, and from instruments to outcomes. Prominent certifications covered include GOTS (Global Organic Textile Standard), Fair Trade Certification, OEKO-TEX Standard 100, Bluesign® Certification, Cradle to Cradle (C2C) Certification, Forest Stewardship Council (FSC) Certification, and GRS (Global Recycled Standard). Each certification targets different aspects of sustainability. Additionally, key standardization frameworks relevant to sustainable textile producers are also examined, notably ISO 14001 (environmental management), ISO 9001 (quality management), and ZDHC (Zero Discharge of Hazardous Chemicals). This chapter further examines persistent challenges and associated findings related to the cost of compliance, the complexity of multiple standards, and the lack of uniformity across different regions.