•This paper tackles the challenges of “resource islands” in disaster response.•It enables multi-discipline multi-actor collaboration for decision support.•Joint exercises and operations in relevant institutions demonstrate its capability.•It is a response to the Sendai Framework. The benefits of geospatial technologies in disaster management have reached a consensus in the international community. However, immediate integration and orchestration of the rich geospatial resources (data, algorithms, computing resources, etc.) in an emergency remain challenging due to the four gaps: encoding gap, source gap, knowledge gap, and network gap. Aiming to bridge the “resource islands”, we propose a service-oriented collaborative approach to disaster decision support by integrating geospatial resources and task chain as domain knowledge into a distributed environment. Data contributors, model contributors, GIS developers, and business experts collaboratively build a spatial decision support system (SDSS) that integrates various resources and knowledge. When disaster strikes, responders collaboratively perform emergency tasks to deliver the right information to the right person at the right time by leveraging the SDSS. The proposed approach is implemented as a Geospatial service platform for Disaster Response (GeoDR). Four joint exercises and the operation in relevant institutions in China demonstrate its capability to facilitate timely and effective responses to natural disasters.