Realising the aspirations of the Sustainable Development Goals (SDGs) to reduce inequality, limit ecological damage, and secure resilient livelihoods is a grand challenge for sustainability science, civil society and government. We identify three key governance challenges that are central for implementing the SDGs: (i) cultivating collective action by creating inclusive decision spaces for stakeholder interaction across multiple sectors and scales; (ii) making difficult trade-offs, focusing on equity, justice and fairness; and (iii) ensuring mechanisms exist to hold societal actors to account regarding decision-making, investment, action, and outcomes. The paper explains each of these three governance challenges, identifying possible avenues for addressing them, and highlights the importance of interlinkages between the three challenges.