The smart city concept is used as tool by local and municipal governments to deliver benefits relating to people, government, economy, mobility, environment and living. By embedding technologies and the internet of things in the city’s infrastructure, smart cities aim to generate insights that drive local im-provements and accrue to a global level. The smart city is also viewed as a transformative lever for government. As cities move beyond smart city pilot showcasing projects, they face the challenge of embedding smart city initiatives in business-as-usual. Despite ambitious goals and high stakes, little is known about the work that leaders perform in undertaking this transformation. This study explored the leadership practice of smart city leaders in Denmark, Holland, USA, Australia and New Zealand. We focus on how leaders drive transformation from showcasing to becoming a sustainable smart city, and the challenges faced. As result we present a framework of six barriers to overcome and five enacted leadership roles to transform the city of today to a future sustainable smart city. We use institutional logics as a lens to discuss and explain the challenges faced by city leaders and their critical role as innovation agents and boundary spanners in smart city transformation.