Unconfined compressive strength tests, direct shear strength tests, and scanning electron microscope microanalysis were conducted to investigate the improvement effect and reinforcement mechanism of the biogel and palm fiber composite on clay. The test results show that the biogel and palm fiber composite can significantly enhance the compressive strength of clay, with a maximum compressive strength of 876.4 kPa, and the optimal mixing ratio is a biogel content of 2% and a palm fiber content of 0.6%. Compared with the clay improved only by biogel, the modified soil exhibits less brittle failure; compared with that improved only by palm fiber, it presents better integrity. Under compression, palm fibers can bridge cracks in the soil, while biogel greatly increases the cohesion of the soil and reduces the outward movement of palm fibers under compression. Scanning electron microscope microanalysis reveals that biogel wraps the soil by forming a film-like structure, and the carboxyl and hydroxyl groups in its molecules bridge and form hydrogen bonds with the surfaces of clay particles, filling interparticle pores to improve soil compactness. Palm fibers mainly exert a physical reinforcement effect, sharing external loads through friction and tension with the soil. Biogel acts as a bonding agent between palm fibers and soil particles, and palm fibers fill the pores of soil particles, optimizing the arrangement structure of soil particles through stretching, interlocking, and friction effects, thereby improving the strength and overall stability of the soil.