A company’s reputation is heavily influenced by sustainability. Furthermore, the recent pandemic has made us more aware of the social dimension of sustainability. Herein, fashion brands also have a role in collaborating and generating a positive impact on society. Hence, the focus of this paper is to examine if sustainability is associated with a company’s corporate reputation among real customers. An analysis of 10 Spanish fashion brands has been conducted, measuring the impact of sustainability on their corporate reputation. Data for this study was collected by surveying 500 Spanish consumers online and quantitative analysis was performed with Partial Least Squares (PLS) v.3.2.7 software. The empirical study does not validate that sustainability positively affects the reputation of Spanish fashion brands, while companies were evaluated negatively when it came to social responsibility or enhancing society. Nevertheless, the company received positive feedback on its environmental stewardship. The other results show that reputation does have a positive effect on trust. It is the most significant direct effect that occurs in the present study. Also, trust has a positive impact on loyalty in Spanish fashion brands.