The main objective of this research is to investigate online purchase behavior of Gen Z in the e-commerce and cosmetics industry in Vietnam.  Quantitative approach with a sample size of 600 have been employed in this research. Furthermore, snowball sampling method and structured questionnaires have been used to achieve research goal. Descriptive statistics are the main analysis method used in this research. The respondents are representatives of the Gen Z group and range in age from 16 to 25.  The results show that female tend to online purchase pretty frequently. However, LGBT people also rank among the gender groupings who purchasing online most frequently. For Z generations in the North and South, online purchasing behavior is a pretty common activity.