The study aims to test ACB attitude models (Affective, Cognitive, Behavior) and their role in online purchasing decisions. The novelty in this research is modifying the ABC attitude model (Affective, Behavioral, Cognitive) into the ACB attitude model (Affective, Cognitive, Behavioral). The study used affective, cognitive, and lifestyle approaches in understanding online consumer buying behavior. Affective is explained by emotions and preferences, while cognitive is explained by perception. Respondents who researched are the millennial generation as consumers of fashion products in e-commerce in Indonesia. Sampling by purposive sampling method. Collecting data by survey method. The data collection instrument is an online questionnaire. The research instrument was tested with validity and reliability tests. SEM analysis shows that online organic marketing stimuli on the website affect online purchasing decisions because it is moderated by lifestyle and mediated by affective-cognitive learning (emotions, preferences, perceptions). The newness of the results of this study is that the ACB attitude model has been empirically tested as a factor that has a significant influence on online purchases. The research findings provide an important meaning for marketing managers to optimize the website as a marketing medium by involving lifestyle factors, affective-cognitive learning (emotions, preferences, perceptions).