["Business Strategy and the Environment, Volume 35, Issue 3, Page 3993-4013, March 2026. ", "\nABSTRACT\nInnovations addressing societal and environmental challenges often emerge within sustainable ecosystems, where diverse actors coordinate their efforts. We argue that the emergence of such ecosystems requires a protected space—one that must be cocreated by both public and private actors. This paper explores how these actors collaboratively establish and sustain protected spaces to enable the emergence of sustainable ecosystems. Drawing on a qualitative analysis of two case studies, we examine how public and private leaders share leadership and cocreate these protective environments. Our findings reveal the mechanisms through which shared leadership is established and public and private leaders mutually empower one another to perform leadership functions. We propose a framework that explains how shared leadership can be structured to support the creation of protected spaces that are conducive to sustainable ecosystems. Furthermore, we show that the involvement of public actors in ecosystem leadership transforms the ecosystem into a political object, introducing new vulnerabilities. The paper concludes by discussing the implications of shared ecosystem leadership for both public and private leaders.\n"]