Climate change, driven by rising carbon emissions, poses significant threats to the environment and human life, including sea level rise and more frequent extreme events such as floods, storm surges, and tsunamis. Highly effective ways to mitigate coastal flooding are building shore-protection systems: seawalls against sea-level rise and armour blocks to dissipate wave energy. However, conventional shore-protection systems, relying on heavy concrete, are too slow to meet the escalating demand and have large carbon footprints. A fundamental change in technology is thus proposed to speed up the construction of more sustainable shore-protection systems. The novel hybrid technology merges techniques from heavy marine concrete-soil and lightweight composite construction. The technology involves building lightweight skins from fiber-polymer composites, which are durable and non-ecotoxic in seawater. The seawall modules consist of a composite skin and skeleton filled with dredged soil, while armour blocks comprise a composite skin filled with pumped lime mortar or concrete. In both, only the skins are transported, sunk and positioned in the sea, and filling occurs on-site. This hybrid-composite technology offers cost-effective, 3–10 times faster construction, with a significantly reduced carbon footprint. It is adaptable and resilient, with the modular design of the seawall allowing for height adjustments to account for progressing sea level rises, and the armour skins providing long-term durability.