Seaports are critical links within supply chains that are often located near residential areas. These seaports can be directly affected by the consequences of operational risk sources and natural disasters such as undeclared dangerous goods and flood, respectively. The diversity and large number of stakeholders at seaports add another level of complexity for risk management that requires a standard approach and clear guidelines. This paper aims to develop a prescriptive process model for cooperative risk management (CoRiMaS) in seaports to enable the stakeholder to manage different sources of risk during risk prevention and response. The prescriptive process model builds on two previous published papers which focused on developing a conceptual framework and a descriptive model based on an ontology for CoRiMaS, respectively. A detailed requirement analysis based on focus groups and a survey study in the Baltic Sea Region (BSR) provide important inputs to integrate the required elements into the CoRiMaS prescriptive process model. The model requires an overall input represented by the type of seaport and structure. The prescriptive process model presents all steps and aspects related to stakeholder analysis, risk governance, risk management, and knowledge management. Implications for theory and practice, as well as an agenda for future research, are presented.