In this study I examine the role of philanthropic foundations in stimulating city government innovation. Reduced budgets and rising consumer demands are challenging organizational capacity in government, prompting government officials to recognize the need for innovation to improve policies, programmes and practices. This empirical study draws upon qualitative interviews and policy reports to generate comparative case studies on three city governments in England: Bristol, Manchester and Newcastle. It builds on work in urban studies and policy mobilities that reveals how foundations can influence urban agendas, finding that philanthropic foundations engage with city governments through three different types of collaboration: direct provision of financial resources, exchange of non-financial resources with city governments and indirect engagements. Philanthropic foundations are blending financial resources and less tangible provision of space and time to enable city governments to experiment with new ideas, policies and ways of working. The fusion of non-governmental resources provides city governments with the capacity to act, and city governments often use non-governmental funding for riskier projects and for projects that may not have taken place if public funding had been used. Through these different collaborations and by deploying a suite of interventions and methods, philanthropic foundations stimulate product, service, process, conceptual and governance innovation in city governments.