The treatment of marine sediment has been a global-scale challenge. Portland cement (PC) is a widely-used binder in the conventional stabilization/solidification method. The use of PC can cause serious environmental pollution. In this context, the environment-friendly binder (blend of quicklime and ground granulated blast-furnace slag (GGBS)) has been adopted to replace PC in the soil remediation field. This study investigated the quicklime-activated GGBS for the stabilization of marine sediment at high water content. The physicochemical and unconfined compression tests were performed to analyze the physical, chemical, and strength characteristics of the quicklime-GGBS stabilized sediments. The results were compared with that of PC-stabilized sediment. As compared to the PC-stabilized sediment, the quicklime-GGBS stabilized sediment would generate larger volume shrinkage, lower water content, and slightly higher density. With reducing quicklime proportion and continuing curing time, the pH of the quicklime-GGBS stabilized sediment gradually decreases. The unconfined compressive strength of the lime-GGBS stabilized sediment shows a trend of first increasing (quicklime proportion of 0.05–0.15) and then decreasing (0.15–0.3) and finally increasing again (0.3–0.4). The maximum strengths appear at the lime-binder ratio of 0.15 and 0.4. The maximum strength at the quicklime-binder ratio of 0.15 is 1.4 times the same as the corresponding PC-stabilized sediment under the same condition. The findings indicate that the combination of GGBS with little quicklime has the potential to replace PC for stabilizing natural sediment at high water content.