Global warming and resource depletion lead ports worldwide to define new strategies for reducing their environmental impacts. The paper offers an explorative analysis of three of Europe’s largest and most polluted ports – Rotterdam, Antwerp, and Hamburg – describing how those ports address the sustainable challenge. Particularly, the analysis is beneficial to decline a recurrent concept, i.e., green port. The concept has been developed to increase environmental awareness and refers to a set of actions describing how the port balances the ecological footprint by economic benefits. Key actions to be sustainable often are mainly attributable to green technology adoption. Instead, the paper focuses on how ports act to be green. Is a green port a port that adopts green solutions for improving operational performance, or does it develop green solutions and guide the green strategy with and for the entire local area? Results show that ports, in addition to adopting intelligent and digital solutions that improve ports’ activities, they act as innovation hubs, building an innovation ecosystem that leads their green transition.