Digital artefacts are increasingly used for supporting innovation practices, implying a growing need to better understand their role in different contexts. In this paper, we study how digital artefacts enable and constrain innovation practices by means of an in-depth, multi-year qualitative field study at a software firm. Analysing the usage of PowerPoint, as a dominant digital innovation artefact, we identify three paradoxes – conflicting yet interdependent tensions of digital artefacts in innovation practices: (1) Freedom and Captivity, (2) Clarity and Ambiguity, and (3) Scarcity and Abundance. Via a dialectic synthesis of the three paradoxes and an extension to modelling tools, we develop a substantive theory of the paradoxical effects of digital artefacts on innovation practices. We discuss theoretical implications for research on affordances and outline a path for research on IT paradoxes. We also offer practical implications by illustrating the paradoxical effects of using digital innovation artefacts and suggesting appropriate coping strategies.