The millennials are an important cohort in luxury market, because of their purchasing power and the power of social media interaction. However, little is known about factors underlying their attitudes toward luxury fashion brands and online purchase intentions. This study explores whether materialism, a need for uniqueness, susceptibility to informative influence, and social media usage affect millennials’ attitudes toward luxury fashion brands and online purchase intentions. In addition, this research examines cross-cultural differences between Russian and Korean millennials based on four cultural dimensions of Hofstede’s model. The results indicated that all factors significantly related to attitudes towards luxury brands, and this, in turn, positively effect on online purchase intentions. Moreover, the results indicated that millennials from Korea and Russia pursue a need for uniqueness, some differences were revealed regarding materialism, susceptibility to informative influence and social media usage. Theoretical and practical implications are further discussed.