Green supply chain management (GSCM) can be defined as the integration of environmental concerns into the inter-organizational practices of supply chain management (SCM). This paper analyzes the role of seaports in the greening of supply chains in two ways. First, the fields of action to pursue GSCM objectives in ports are identified and grouped. The proposed typology includes five groups of actions, i.e., green shipping; green port development and operations; green inland logistics; seaports and the circular economy; and, actions in the field of knowledge development and information sharing. In the empirical part of the paper, this typology is used to analyze green actions and initiatives developed by market players and port authorities in the Rhine–Scheldt Delta, the leading European port region in cargo throughput terms. This structured overview of green actions and initiatives shows that these ports are hotbeds for GSCM initiatives, but progress in some areas remains slows. The second part of the analysis focuses on the attitudes and perceptions of port-related actors towards the greening of port-related supply chains. A large-scale survey conducted in the Belgian and Dutch logistics and port industry reveals that greening has been put massively on the agenda by the firms between 2010 and now. The results give a clear view on the diverse drivers and impediments towards the greening of supply chains. In addition, one can still see a gap between words and actions. The survey further points to the role of governments as catalysts or soft enforcers for change, and calls for continuity and coherence in government policy. This paper is the first study providing a comprehensive analysis on initiatives, approaches, and perspectives of port-related actors in a specific multi-port region.