Purpose The growing competition in Malaysia’s modest fashion industry has proven to be the main challenge for the business to stay relevant in the market. Based on this reason, it is vital for marketers to create a differentiation in their brands to attract more customers. One of the ways to create this differentiation is by establishing brand personality. Brand personality does not only differentiate from one product to another but is also a common strategy used by marketers to create competitive advantage for their business. Although brand personality has been studied on various product brands, limited research has been done on Muslim products, especially modest fashion apparel. Because modest fashion is considered as Muslim products in Malaysia, this paper aims to examine the relationship between Halal brand personality and brand loyalty with the aim of providing a better understanding of the Islamic marketing concept. Design/methodology/approach Descriptive survey design was conducted to measure consumer behavior, attitude and perception within a specific period. A total of 400 respondents were identified for the study. Purposive sampling was chosen for this study because the respondents are expected to have same set of characteristics and perceptions toward the phenomena. Five-point Likert scale was used to assess consumers’ perception of the relationship between Halal brand personality and brand loyalty. Last but not least, SPSS software (Version 22.0) was used to analyze the data through multiple regression analysis. Findings The result indicated that only three out of five Halal brand personality dimensions have a significant relationship with brand loyalty. The three significant dimensions are excitement, sophistication and righteousness. It can be concluded that modest fashion brands need to include all of the three dimensions in their branding strategy. Research limitations/implications Two main limitations in this study is that it was conducted only in a stipulated period and it focused only on one generational cohort, which is millennial consumers. Practical implications This study provides new recommendations to the knowledge gap of brand personality introduced by Aaker (1997). It helps the marketers and researchers to understand the importance of emphasizing religious values in marketing Halal products to their consumers. This study further recognizes the relationship between Halal brand personality and brand loyalty, particularly with regard to millennial’s modest fashion consumption. Originality/value Brand personality has received levels of attention from academics and practitioners alike; however, there is a lack of research on Halal brand personality in marketing field, particularly on its relationship with brand loyalty. To the best of the authors’ knowledge, this study presents the first empirical test of the direct effect of Halal brand personality and how it drives millennial consumers’ brand loyalty.