Previous sociolegal research has neglected how the work of corporate security agents is enabled and constrained by legal knowledges. This article explores how legal knowledges shape the work of municipal corporate security (MCS) agents in Canadian cities. MCS offices are a new development in municipal governments. By drawing on analysis of freedom of information requests and interviews with MCS managers and staff, we investigate how legal knowledges shape MCS practices in Canadian cities, with a focus on trespass law, licensing law, litigation, labor law, privacy law, and workplace violence legislation that converge in MCS offices. MCS agents must interpret, translate, and apply these laws in their municipal jurisdiction or urban problem space to confront the defining element of the urban milieu—nuisance—but also to mitigate the risks. Interpretation and use of numerous laws by MCS staff constitute a distinctively urban way of governing through legal knowledge.