This paper assesses the potential of the circular economy (CE) policy ambitions of the port cities of Ghent (Belgium) and Amsterdam (The Netherlands). Both Ghent and Amsterdam are municipalities that potentially lend themselves ideally to set up a more local-oriented circular (re)production and (re)consumption system. Subsequently, both have the ambition that, in 2050, the CE will have become an achieved public value that influences all activities to be more circular in comparison with today. However, while having ambitious policies is important, we explain that a public value also requires alignment with the operational capacity used or needed to achieve this policy ambition. In this paper, we focus on the ‘negative’ CE operational capacity: landfills and incinerators. Our results show that the CE ambitions of Ghent are more realistic than Amsterdam. During the last few decades, Dutch waste management has been largely privatized. This led to a significant increase in incinerator capacity and a lowering of the incineration price. This differs from Flanders, which has a deliberate capping on the allowed incinerator capacity, keeping the price for incineration high. This increases the incentive for urban and maritime actors to climb the waste hierarchy, eventually thus making the port city (potentially) more circular as a whole.