Stabilization/solidification (S/S) has been examined as an effective way to strengthen soft soils. However, the presence of organic matter (OM) in dredged marine silt can substantially weaken the reinforcement effect of S/S. To treat organic silt that is difficult to strengthen by S/S, a new combined application of S/S and electroosmosis (EO) treatments was adopted in this paper to increase the strength of soft soil. To enrich the current knowledge about combined soft soil treatment methods, as well as to study the mechanism of increasing the strength under combined S/S-EO treatments, silts with different OM and cement contents were stabilized, and then EO was carried out after certain precuring times. Different test methods, including bearing capacity tests, scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP), etc., were conducted. The experimental results showed that both OM and cement can reduce the EO resistivity of samples, and the combined application of S/S-EO treatments can significantly improve the bearing capacity of organic silt, with a maximum increase of 80.5%. Additionally, the combined application solves the problem of soil cracking and detachment between electrode and soil. Finally, the micromechanism of S/S-EO is discussed considering the number of cement hydration products and pore diameter.