This paper investigates the emergence of employee engagement through the process of transformative sustainable business model innovation (SBMI) within an established organization. Although SBMI offers both societal and organizational benefits, the current literature lacks a comprehensive understanding of the transformative processes involved in developing and adopting these models. Recognizing the critical role that employees play in these transformations, we aim to examine how their engagement emerges. Based on a qualitative case study of a mature nuclear-based organization, our findings show that employees engage in a triple-path process by leveraging a managerial directive to develop intrapreneurial creativity, which is followed by experimentation to develop new sustainable models. The conditions of meaningfulness and complementarity between social and economic goals conditions employee engagement. Our paper contributes to the SBMI literature by highlighting a bottom-up, collaborative approach to transformation where sustainability is a byproduct of meaningfulness. Meaningfulness is theorized as an embedded social condition rather than a simple psychological predisposition. From a practical perspective, we advocate for forums to encourage intrapreneurial creativity for incumbent firms seeking transformation in their business models
