The intensity of competition has made it difficult to maintain the loyalty of current customers to business organizations; thus, brands must pri-oritize developing lasting relationships with customers. Therefore, this study aims to explore the relationship between brand DNA and customer loyalty to a brand. A pre-structured and pre-prepared survey list was used to collect data from Egyptian customers of the most famous fast fashion brands in Egypt (Zara, H&M, Mango, Stradivarius, Pull & Bear, Bershka, LC Waikiki, Max, American Eagle). This was done using a non-probability quota sample with a sample size of 384 individuals. The data were then analyzed using appropriate statistical methods. The study found a statistically significant positive relationship between brand DNA and customer loyalty to a brand. The findings contribute to the development of marketing knowledge in the fast fashion industry, improve marketing practices, and open new horizons for future research in this area.