The impact of digital transformation (DT) on open innovation (OI) has attracted growing interest. However, the nuanced effects of various forms of coupled OI on innovation outcomes remain underexplored. This study aims to investigate the differential impacts of coupled OI modes on innovation performance within the context of DT driven by Industry 4.0 technologies. To test the hypotheses, we used Heckman's two-stage estimation utilizing the Korean Innovation Survey 2022. The findings reveal that collaborative activities as coupled OI modes positively impact innovation performance. Furthermore, the adoption of Industry 4.0 technologies amplifies the positive impact of research and development (R&D) collaborations on business process innovation while diminishing the positive effect of non-R&D collaborations on new product development. This study's contribution to the literature lies in its finding that the adoption of Industry 4.0 technologies can only be beneficial to firms when DT guides the focal firm on being more cooperative in R&D collaboration activities and therefore helps focal firms to use innovation opportunities efficiently and more rapidly and to innovate diverse business processes. In practice, a firm should have sufficient capabilities to rigorously analyze DT-adoption data to capture market needs.