Online buying is a sort of e-commerce that allows customers to purchase products directly from sellers via a mobile application or an online web platform instead of physically visiting a store. This has enabled customers to shop at their leisure, 24 hours a day, seven days a week. This study aims to examine the association between product price, product quality, and online advertisement on the online buying behaviour of working adults towards branded home electronic products in Penang, Malaysia. The Theory of Reasoned Action was used as the foundation of the conceptual framework. A total of 417 respondents in Penang were involved in this study using an online survey questionnaire. A multiple linear regression analysis was used to evaluate hypotheses. The results revealed that product price and quality significantly influenced the online buying behaviour of working adults towards branded home electronic products in Penang, Malaysia. At the same time, the online advertisement did not show a significant influence.