Interest in system innovation is motivated by the realisation that system-wide change is necessary to make economies socially, economically and environmentally sustainable. Although many national governments have put sustainability and green growth objectives at the centre of their economic development strategies, achieving this goal will require wide-ranging changes in their underlying economic, technological and social systems, from transport, water and energy systems to modes of consumption and waste management. Ensuring that socio-technical systems move towards greater sustainability is a major challenge for governments but also for civil society. At the core of the transition is a shift in governance structures that not only allows change to occur but also directs and orchestrates some of the changes. The smart city initiatives that mobilise technological and social innovations to make the production and consumption of a city’s goods and services more sustainable illustrate this point.