Purpose: The primary objective of this study is to investigate the impact of website quality on impulse buying of the online retailer, which is mediated by positive emotion and moderated by personalized advertising. Research design, data and methodology: The present study used a survey methodology conducted on many user's smartphones. The sample in this study included 409 college students in Indonesia. Purposive sampling was used as the sampling technique. Data was collected by distributing questionnaires to many respondents through the Google Documents online survey. Results: The findings derived from the application of structural equation modelling for data analysis show that 1). Website quality affects impulse buying and positive emotion, and 2). The impact of website quality on impulse buying was mediated by positive emotion and moderated by personalized advertising. Conclusions: The findings presented in this study has significant theoretical implications that contribute to the existing concept on the relationship between website quality, positive emotion, personalized advertising and impulse buying. The findings of the research possess managerial implications. It can be used can as a reference in determining website quality and the appropriate personalized advertising that increases online impulse buying at online retailer In Indonesia.