Many cities are experiencing long-term declines in population and economic activity. As a result, frameworks for urban sustainability need to address the unique challenges and opportunities of such shrinking cities. Shrinking, particularly in the U.S., has led to extensive vacant land. The abundance of vacant land reflects a loss of traditional urban amenities, economic opportunity, neighbors, businesses, and even basic city services and often occurs in neighborhoods with socially and economically vulnerable or underserved populations. However, vacant land also provides opportunities, including the space to invest in green infrastructure that can provide ecosystem services and support urban sustainability. Achieving desirable amenities that provide ecosystem services from vacant land is the central tenet of a recent urban sustainability framework termed ecology for the shrinking city. An agroecological approach could operationalize ecology for the shrinking city to both manage vacancy and address ecosystem service goals. Developing an agroecology in shrinking cities not only secures provisioning services that use an active and participatory approach of vacant land management but also transforms and enhances regulating and supporting services. The human and cultural dimensions of agroecology create the potential for social-ecological innovations that can support sustainable transformations in shrinking cities. Overall, the strength of agroecological principles guiding a green infrastructure strategy stems from its explicit focus on how individuals and communities can shape their environment at multiple scales to produce outcomes that reflect their social and cultural context. Specifically, the shaping of the environment provides a pathway for communities to build agency and manage for resilience in urban social-ecological systems. Agroecology for the shrinking city can support desirable transformations, but to be meaningful, we recognize that it must be part of a greater strategy that addresses larger systemic issues facing shrinking cities and their residents.