Decontamination of radioactive materials in the soil during the decommissioning of nuclear facilities is a challenging issue. Among the radioactive materials, cesium (Cs) is the most concerning radionuclides due to the inherent characteristics like long half-life time and high affinity with clay minerals. A process is required to treat the soil contaminated with radioactive materials generated during decommissioning the nuclear facilities. Remediation of Cs-contaminated soil is carried out to reach the feasibility of desorption of Cs from the soil and reduce the radioactive wastes. We proposed the “Extraction-selective adsorption-disposal” process as a method to treat Cs-contaminated soil. First in the extraction step, using soil washing, Cs+ attached to the soil could be separated into the solution by ion exchange. Among the extraction agents tested in this study, KCl showed relatively better extraction performance for Cs+, that is, 30 and 40 % from soil 1 and soil 2, respectively. However, the extraction of Cs+ by KCl is not enough to meet the decontamination goal, and enhanced extraction is required. The hydrothermal extraction and 3 times multi-step extraction were proposed to enhance the extraction of Cs+ and increased up to 70 %. The selective adsorption of Cs+ from the extracted solution was performed to figure out if Cs+ can be selectively removed from the wastewater of the extraction process in the presence of a high concentration of KCl. However, unfortunately, the presence of K+ hindered the adsorption of Cs+ onto adsorbents due to the structural similarity of the two ions. Especially, the high concentration of K+ inhibited the adsorption of Cs+ greatly even onto the Prussian blue modified zeolite. In both extraction and selective adsorption step, K+ acts as an important cation to desorb Cs+ from the soil and inhibit the adsorption of Cs+ onto zeolite.