With global urbanization on the increase and cities now hosting more than half of the planet's population, there are concerns regarding the protection of urban commons as part of sustainability efforts, especially in sub-Saharan Africa. Decentralized urban planning is a policy tool and practice that is used to organize urban infrastructure for sustainable development. Yet, how it can be used to sustain the urban commons remains fragmented in the literature. This study reviews and synthesizes urban planning and urban commons literature using the Institutional Analysis and Development Framework and the non-cooperative game theory to identify how urban planning can protect and sustain the urban commons – green commons, land commons, and water commons – in Ghana. The study, based on the determination of different theoretical scenarios for the urban commons, identified that decentralized urban planning can help sustain the urban commons, but it is operationalized in an unfavorable political environment. For green commons, there are competing interests and poor coordination amongst planning institutions, and the absence of self-organizing bodies in managing the use of such resources. For land commons, increased land litigations are characterized by corruption and poor management of land cases in the formal land courts, and despite the existence of self-organizing institutions, these institutions have failed to act responsibly to protect land commons due to the increasing demands and values (profitability) of lands in urban areas. For water commons, urban planning has not been fully decentralized and there is also the absence of self-organizing bodies in urban water use and management. This is coupled with the waning of customary water protection provisions in urban centers. Based on the findings, the study generally proposes institutional strengthening as the bedrock for enhancing the sustainability of the urban commons through urban planning and should therefore be of policy focus moving forward.