This study focuses on the behavioral intention to purchase groceries from virtual supermarkets by millennials. This research also aims to compare the influencing factors between Thai and Indonesian consumers. The study applies the Technology Acceptance Model (TAM), which is widely accepted to study technology adoption. The hypotheses are constructed to test four independent variables, which are social influence, perceived usefulness, perceived ease of use, and trust and security, and their effects on consumers’ attitudes and intention to purchase grocery online. This study uses a survey to collect data from 400 respondents, 200 who are Thai millennials and 200 who are Indonesian millennials. The results show that perceived usefulness and trust and security are significant factors affecting both Thai and Indonesian consumers’ intention to adopt online grocery shopping. In addition, perceived ease of use has an effect on the intention to adopt online grocery shopping only for Thai millennials while social influence has an effect only on Indonesian millennials’ intention to adopt.