Although the synergy between port and city is usually perceived as a fact, the two elements of the port city have been developing separately, both spatially and functionally. Economic development, a vital component of the urban socio-economic system, can be considered one of the sectors where port-city synergy is crucial. However, at the same time port cities need to build climate resilience because of their high exposure to climate extremes. The value of assets at risk and the economic importance of port cities, influencing their extended hinterlands and the global economic networks, highlight the need for adaptation to climate change. Following this rationale, this research studies 40 port cities in 16 countries around the world. By collecting the separate climate change adaptation actions of the ports and the cities, and correlating them with Relative Concentration Index (RCI), the study explores how the port-city relationship is linked to the adoption of distinct types of adaptation actions by the port authorities and local governments, in some of the most exposed port cities globally. The results reveal the dependence of the city's adaptation response on the port-city relationship, as well as opportunities for multi-level and multi-scale collaborations between ports and cities. The benefits of synergies extend from the local to the global level, starting from climate change and aiming to build infrastructural, social and economic resilience.