Sustainability in fashion gained importance more than ever recently. Having evolved in time and been influenced by the Covid-19 pandemic, sustainability is positioned within an axis that affects not only law and regulations but also producers and consumers. This chapter explores sustainability in fashion from various perspectives, including governmental regulation, production, marketing, and consumption. In the first section, a historical background of sustainability is given, followed by the relevant sustainability concepts in fashion supply chain, marketing, and retailing. The adoption of sustainability in fashion supply chains and retail businesses is described with numerous recent examples and cases, with a special emphasis on some practices in regard to the circular economy and blockchain operations. This section ends with the effects of the Covid-19 pandemic on sustainability. In the following section, a broad overview is provided for the consumer behavior studies established in the last 5 years, which are summarized to gain consumer insight on sustainability. In this respect, the consumer behavior and consumption patterns that address the sustainable fashion products in general, the sustainable fashion products produced by using environmentally friendly materials and ethical approaches, and the sustainable fashion products delivered via collaborative consumption-based models are given. Moreover, the approaches of distinctive consumer groups (belonging to different cultures, genders, ages, and generations) towards sustainability concepts and sustainable fashion products are explained. Each subsection ends up with practical insights for the practitioners. The last section covers the findings of an empirical study whose aim is to explain the motivations beyond the sustainable fashion consumption that are expected to be triggered because of the Covid-19 pandemic for Generations Y and Z. Based on the conceptual framework proposed for combining individual beliefs (about self-interest motives and pro-social motives) by employing an integrated model of the TPB and NAM model, the findings are presented for the generations in concern. This subsection ends with the recommendations for appropriate marketing strategies.