Cities worldwide are rising to the challenge of sustainable development, calling for large-scale and fast-paced transformations towards sustainability. Urban sustainability challenges are now being reframed as a lack of capacity of individuals and organizations to carry out such socio-technical transformations. This article expands on transformative capacity literature by elucidating the concept of actor-centric transformative capacity. It focuses on the unique role city-university partnerships (CUPs) can play in catalyzing and supporting effective urban sustainability transformations. Two case studies on CUPs in Portland, Oregon and Tempe, Arizona are used to identify determinants of actor-centric transformative capacity, their role in the transformative capacity of urban systems, and how they are built through CUPs. The article concludes with strategies for building effective CUPs capable of building actor-centric transformative capacity among university actors and city administrators.