Urban landscapes can be transformed by widespread abandonment from population and economic decline. Ecological assembly, sometimes referred to as “greening”, following abandonment can yield valuable ecosystem services, but also can pose a risk to public health. Abandonment can elevate zoonotic vector-borne disease risk by favoring the hyperabundance of commensal pests and pathogen vectors. Though greater biodiversity in abandoned areas can potentially dilute vector-borne pathogen transmission, “greening” can elevate transmission risk by increasing movement of pathogen vectors between fragmented areas and by giving rise to novel human-wildlife interfaces. Idled and derelict infrastructure can further elevate disease risk from vector-borne and water-borne pathogens, which can build up in stagnant and unprotected water that maintenance and routine use of delivery or sanitation systems would otherwise eliminate. Thus, framing “greening” as inherently positive could result in policies and actions that unintentionally exacerbate inequalities by elevating risks rather than delivering benefits. As counter-urbanism is neither a minor pattern of urban development, nor a short-term departure from urban growth, homeowner and municipal management of abandoned areas should account for potential hazards to reduce health risks. Further socioecological assessments of public health risks following abandonment could better ensure the resilience and well-being of communities in shrinking cities.