Over the last decade many large world cities have scaled up efforts at climate adaptation, a primary focus of which is protecting population health. With extreme weather disasters increasing worldwide, public health agencies are among local institutions under greatest stress; the Covid-19 pandemic has only heightened pressure on these agencies. Yet the limited literature examining adaptation actions across world cities suggest few, mainly high-income cities report health-related adaptation, while city public health agency engagement in adaptation has received little research attention. In this comparative review, we aimed to characterize the public health role in the adaptation plans of 22 large cities pre-identified as highly health-adaptive, by examining five health-associated adaptation activities chosen as “promising practice” based on evidence synthesized from evaluation research and practical experience: (i) hazard and vulnerability mapping; (ii) extreme weather preparedness and response; (iii) extreme heat plans (including heat early warning); (iv) non-heat early warning (e.g., flooding, vector-borne disease); and (v) climate-health monitoring and outcome surveillance. We found most (90%) city adaptation plans reported actions in at least three of these five activity areas. However, only 73% of these health-focused plans reported involvement of a public health agency (though the share was higher for cities in low- and middle-income countries). We detected differences across the five activities, including an ascending pattern of public health engagement starting with heat plans and including activities such as preparedness and mapping as health agency involvement increased. We also identified substantial presence of other city agencies–notably urban planning, emergency management and public utilities–in implementing these health-associated activities. With every world region likely to experience more widespread and intensifying climate impacts, and growing pressure on local public health agencies in conjunction with the Covid-19 pandemic, we identify opportunities for enhancing public health engagement in climate adaptation in large cities with a view to scaling up their ability to contribute to climate adaptation goals.