Urbanisation, population growth and climate change, among other challenges, have put pressure on urban infrastructure systems, prompting a shift from large-scale centralised infrastructure to localised nature-based solutions. Mainstreaming nature-based solutions requires a change in the planning and governance systems, and mediating new relationships and configurations between different actors through collaborative governance. Yet, limited guidance exists on how to design collaborative governance for delivering nature-based solutions. This has led to collaboration processes that are established on an ad-hoc basis, relying on the experiences, skills and viewpoints of their champions to endure. This paper synthesises and extends a suite of theoretical frameworks with the practice-based knowledge of urban practitioners across Australia (n = 42), to develop a framework for designing collaborative governance. The framework offers key principles and considerations for designing collaborations on nature-based solutions. It emphasises upfront planning that carefully considers the desired outcomes (the ‘why’), assesses the operating environment/context (the ‘what’), engages the right actors at the required level of influence (the ‘who’), and uses fit-for-purpose structures and process for interaction (the ‘how’). The framework also highlights that all those elements need to be considered with the intended level of impact in mind. To illustrate the application of our framework, we will use empirical examples from major urban development programs across Australia that have adopted water sensitive urban design (as part of the broader family of nature-based solutions) through cross-sectoral collaborations.