Social innovation addresses the challenge of achieving climate-neutrality with a collaborative, bottom-up, holistic, and people-centred approach. In doing so it effectively accelerates the pace of change by onboarding diverse communities to the mission. It uses prototyping and quick experimentation to create new products or services, or to implement innovative business models that improve community well-being and promote behavioural change by responding to local needs and acting within a cultural context. This approach complements technical innovation, ensuring economic development and overall well-being while reinforcing the co-benefits of climate mitigation like public health, job creation, and public budget savings. Key Principles for Cities: 1. Collaborative Approach for People-Centred Solutions: Engaging diverse local actors, social innovation helps cities articulate and address collective needs, accelerating emission reductions with practical solutions and cultivating shared buy-in. 2.Address Unmet Social Needs: Social innovation provides new ideas and solutions for people to adopt climate-neutral lifestyles, benefiting both people and the planet. 3. Activate an Ecosystem: Empowering diverse local actors, cities create platforms for climate transformation, fostering inclusive, adaptive, and resilient local ecosystems.