Peat soil is formed through the accumulation of undecomposed plant organic matter, resulting in a high fiber content that leads to poor physical properties and low shear strength. Consequently, peat soil is identified as problematic and detrimental in infrastructure construction. One proposed method to improve its physical properties and enhance shear strength is biological soil stabilization through biotechnology, with bioaugmentation as an environmentally friendly alternative. The objective of this research is to accelerating the decomposition of peat fiber by Pseudomonas taiwanensis bacteria, thereby accelerating soil compaction and improving its physical properties and shear strength. The subject of this research is fibrous peat soil in Bereng Bengkel Village, Palangkaraya, Central Kalimantan. From the experimental results, it was found that the addition of 15% Pseudomonas taiwanensis bacteria to fibrous peat can significantly improve the physical properties and shear strength. Thus, Pseudomonas taiwanensis bacteria can be used as an environmentally friendly alternative to improve the geotechnical properties of fibrous peat.