We investigated whether there is a causal relationship between the presence of customizability technology (i.e., technology that allows individuals/websites to tailor the information environment according to user's preferences) and political selective exposure. We found that various forms of customizability technology (especially, system-driven customizability) increase selective exposure in the context of online political news consumption. Moreover, customizability technology has a stronger effect on minimizing exposure to counter-attitudinal information than it has on increasing exposure to pro-attitudinal information. The effect of customizability on selective exposure was particularly strong for ideologically moderate individuals. This study extends the understanding of the selective exposure process in today's communication environment and clarifies the implications of the Internet for deliberative democracy theory.