Uncrewed systems are increasingly emerging as a new class of military technology, as demonstrated by their extensive and evolving use in recent conflicts, such as the war in Ukraine. Within the maritime domain, Large Unmanned Surface Vessels form a key element of this broader development. These vessels are viewed as important enablers for future naval operations in which risk reduction, endurance, and persistent presence are dominant drivers. While enabling technologies for uncrewed operation are rapidly maturing, the configuration of naval LUSVs and the associated design decisions are not yet crystallized in the same way as for conventional crewed vessels. As a result, there is a lack of structured approaches to translate naval mission needs into LUSV concept designs. This research addresses this issue by developing and applying a mission-driven design framework that supports the systematic generation of LUSV concept designs. The main result of this research is a stepwise design method that links mission analysis, capability definition, and modular function deployment to conceptlevel vessel designs. The application of the method resulted in several LUSV concepts, illustrating different approaches to mission integration and platform configuration. The results demonstrate how a mission-driven and modular design approach can be used to structure the early-stage design of LUSVs. The derived concepts show how different mission groupings and propulsion requirements lead to distinct platform configurations, providing insight into the trade-offs between flexibility, specialization, and platform commonality. Beyond the case of LUSVs, the approach presented in this research contributes to the systematic design of complex, mission-driven systems. The framework is transferable to other systems and supports transparent concept exploration in domains characterized by emerging technologies and limited design precedent. In these domains, structured design methods are essential to support informed early-stage decision-making.