This article reports some of the results of an experimental research dealing with the reuse of two highly impacting wastes of marine origin, i.e., dredged sediments and mussel shells. Traditionally, commercial cement has been for long used for the mechanical improvement in ex-situ management options of dredged sediments. However, the environmental impact of cement production pushes toward more sustainable binder materials. This study contributes to such a general objective by investigating the effectiveness of shell powder as a partial replacement of cement for the stabilization of dredged sediments. Specifically, the experimental programme involved both traditional cement-based sediment stabilization solutions and original ones where different sediment-shell powder-cement mixtures where prepared and tested. The results of multiscale investigations, including physicochemical and geomechanical tests, indicate a promising potential for mussel shells to reduce compressibility and increase strength properties of sediments, thus contributing to more sustainable waste management practices.