Integrating Information and Communication Technologies (ICT) for meaningful constructivist instruction has become essential in teacher education. This study investigated preservice teachers' intention to integrate ICT for constructivist learning from the perspectives of their Internet epistemic beliefs (IEB) and Internet-based learning self-efficacy (IBLSE) using the structural equation modeling technique. Participants were 403 elementary preservice teachers in Taiwan. Analysis results showed that stronger IBLSE predicted higher intention for constructivist ICT integration into instructional practices. Believing that the Internet-based information is fragmented (structure belief) and requires justification from multiple sources (justification belief) was associated with higher IBLSE. The structure and justification beliefs also indirectly correlated with the intention of constructivist ICT integration via preservice teachers' IBLSE. Findings can inform instructional practices and interventions pertinent to enhancing preservice teachers' IEB and IBLSE to promote their future constructivist ICT integration in their instruction.