External stakeholder support is critical to the success of megaprojects, necessitating strategic engagement, often using Information and Communications Technology (ICT). We conducted 30 semi-structured interviews with a megaproject team and analysed their social media communications with the project community. The findings show three ICT practices used for managing external stakeholders: visualisation, simulation and social mediatisation. Taking a sociomateriality lens we demonstrate how these practices are used for diverse unintended uses to manage external stakeholders. Anchored in a dimensions of power framework, we discuss how these ICT practices were strategically used for persuading, framing and hegemonizing external stakeholders in megaprojects. Theoretically, we highlight the role of ICT for managing external stakeholders over the current use of improving the competitive advantage of internal stakeholders. Practically, social media is used to articulate practices in all the strategic roles, positioning it in a role as a critical ICT tool for external stakeholder management in infrastructure megaprojects. © 2020 Informa UK Limited, trading as Taylor & Francis Group.