This research examines the relationship between personality traits and consumer behavior in purchasing fashion apparel on electronic commerce platforms. An online questionnaire was developed to survey 214 male and female respondents, aged between 18 and 35 years, living in Bangkok with prior experience of purchasing fashion apparel through an electronic commerce platform within the last three months. The research findings revealed that the most dominant trait among the respondents is Agreeableness, followed by Openness to Experience, Conscientiousness, Extraversion, and Neuroticism, respectively. Four out of five dimensions of personality traits manifest a positive relationship with different aspects of consumer behavior. For consumer motivations, hedonic motivation can be linked with Extraversion. In terms of search behavior, a positive relationship is exhibited between goal-directed search and Agreeableness, as well as between experiential browsing and two traits—Conscientiousness and Neuroticism. Meanwhile, consumer attitude towards purchasing fashion apparel on electronic commerce platforms was found to correlate with three personality traits, which are Extraversion, Conscientiousness, and Agreeableness. Finally, purchase intention is positively related to Extraversion.