This paper experimentally investigated the effect of using nanomaterials to improve soft soils. Laboratory experimental tests were carried out on loessial soils collected from two different sites in Romania. Two different types of nanomaterials were used in this research, which is namely Nano-MgO with different percentages (0.5%, 0.75%, 1%, and 2%), and Nano-Al2O3 with percentages (0.5%,1%, and 2%), were added to the soil samples, to study their effect on the strength, consistency limits and compressibility of the soil. Treated soil samples were compacted using the modified Proctor test procedure and tested. The results of the investigations showed that the addition of nanomaterials to the soil may help to enhance the geotechnical properties. the compressibility and the strength of the treated soils increase with the increase in the amount of nanomaterials, Also, the addition of nanomaterials to the cohesive soils showed a small effect on the microstructure of the soil samples. As expected, the improvement is dependent on the type and amount of the nanomaterials. The results have been compared with 2% soil mixtures with cement.