<p>Ordinary Portland cement (OPC) is the most commonly used binder for the solidification/stabilization of dredged sediments. However, the production process of OPC causes high CO₂ emissions and the consumption of large amounts of nonrenewable resources. Additionally, the solidification/stabilization treatment of sediments with high moisture and organic matter contents requires the addition of a large amount of OPC, which not only increases the cost but also has limited solidification effectiveness. Therefore, there is an urgent need to develop new types of sustainable, effective, and inexpensive binders to replace OPC for the solidification/stabilization treatment of dredged sediments with high moisture and organic matter contents. For this purpose, this study proposed a novel solid waste based binder to solidify the dredged sediment with high moisture and high organic matter contents. The solidified dredged sediment could be reused as the liquefied stabilized backfill material (LSBM) for urban underground space. The research evaluates the effects of initial moisture content, organic matter content, and binder content on the fluidity and unconfined compressive strength (UCS) of solidified dredged sediment. Meanwhile, the curing mechanism is assessed through pH value, electrical conductivity, and scanning electron microscopy (SEM) tests. The results indicate that the fluidity and UCS of LSBM meet the requirements for engineering applications. Compared with treatment with OPC, treatment using the solid waste-based binder reduces the cost and ECO₂ of LSBM by 17.2% and&#xa0;59.7%, respectively. The environmental and economic benefits are notable. The main products of the LSBM are ettringite (AFt) and C–S–H gels, and the specimens are denser than the OPC-treated specimens. Therefore, it is feasible to produce LSBM using solid waste based binder to solidify dredged sediment with high moisture and high organic matter content.</p>