The large amount of waste mud generated during construction projects makes it difficult to implement closed-loop on-site treatment, resulting in the inability to achieve zero emissions, which not only wastes land resources but also pollutes the environment. This article first studied the flocculation effect and mechanism of two flocculants. Then, the treated sediment was used to prepare fluidized solidified soil, and the effect of flocculants in the sediment on the performance of fluidized solidified soil was studied. Finally, this technology of flocculation and re-solidification was applied in engineering. The results showed that the composite effect of adding PAC flocculant first and then APAM flocculant in the mud had the best mud-water separation effect. The soil was combined with the flocculants to prepare fluidized solidified soil that can effectively improve the strength and water stability of the solidified soil. Through engineering applications, it has been proven that closed-loop utilization of engineering waste mud can be achieved on-site. Therefore, this work provides a new method for achieving zero emissions through closed-loop utilization of engineering waste mud on-site and innovative experience for the construction of “waste-free cities”.