Indonesia’s peatlands are concentrated in three major islands, namely Sumatra (35%), Kalimantan (32%), Papua (30%), and other islands (3%) of a total area of 21 million ha. Peat has a low carrying capacity. The carrying capacity of the soil is largely determined by the value of the water content contained in the peat. To overcome this problem, stabilization is carried out using a mixture of biopolymers to increase the carrying capacity of the soil. In this study, testing of the physical properties of peat soil was carried out in order to determine changes in the value of the physical properties of the soil that occurred after stabilization. The sampling location is in the area of Palangka Raya City. There were 5 variations of samples made for stabilizing peat soil with a mixture of 0.5%, 1%, 2%, 2.5%, and 3% biopolymer. The final results obtained after testing the physical properties of post-stabilization peat soil were a decrease in water content in the 3% biopolymer (395.13%) variation, the maximum decrease in fiber content in the 3% biopolymer (30.79%), and the maximum ash content obtained in the 3% biopolymer increasing the value of the bulk density at 3% bipolymer (1.64%), and increasing organic content (96.62%) at 3% biopolymer variation.