Few studies have examined transnational actors involved in global adaptation governance, despite their growing influence. This paper focuses on 100 Resilient Cities (100RC), a transnational municipal network (TMN) that has created governance instruments with potential for contributing to global adaptation governance. Despite their different nature from international actors (states and intergovernmental organizations), the distinct practices of TMNs and how they might influence global adaptation governance are uncertain. Vague claims suggest that TMNs are innovative, but what this innovation consists of remains unclear. Therefore, the research question here is: how do TMNs innovate in global adaptation governance? This paper strives to answer this question, by building an analytical framework to identify types and features of governance instruments, based on the literature on policy instruments, global environmental governance and global climate governance. It presents a case study of 100RC, based on an in-depth documentary analysis and semi-structured interviews. The results suggest that TMNs can be innovative, if they, like 100RC, create original governance instruments instead of using the existing tools of international or other transnational actors. While some of 100RC’s tools favour a more recent, soft and indirect approach, its considerable use of hard practices with significant obligation is particularly interesting considering the general characterization of TMNs as voluntary and soft. The governance practices of 100RC are thus not in stark contrast with those of international actors. Their diversity could provide inspiration for future action to improve the effectiveness of global climate adaptation governance, and the analytical framework developed here could be applied in further studies.