Biochar is defined as an organic material produced by high-temperature burning of plant straw under anaerobic or low-oxygen conditions. It possesses characteristics such as high specific surface area, high pH value, and high cation exchange capacity. The spatial structure of soil is improved by biochar. Microbial growth is favored by biochar. Biochar was combined with microbial induced calcium carbonate precipitation (MICP) technology for silty clay solidification. Different biochar contents and different microbial ratios were applied. Unconfined compressive strength tests, scanning electron microscopy (SEM) observations, X-ray diffraction (XRD) tests, and Fourier transform infrared spectroscopy (FTIR) tests were conducted on the solidified samples. The solidification effect and mechanism of biochar combined with MICP on silty clay were studied. First, MICP solidification of silty clay was performed using bacterial solution and cementation solution with volume ratios of 2∶8, 3∶7, 4∶6, and 5∶5. The unconfined compressive strength of the samples was measured. Without biochar addition, the ratio of 4∶6 for bacterial solution to cementation solution was analyzed to provide the best MICP solidification effect. Second, the bacterial solution to cementation solution ratio was maintained at 4∶6. Solidification tests combining biochar and MICP were conducted with biochar contents of 4%, 8%, and 12%. The unconfined compressive strength index was used. The optimal biochar content was determined as 8%. Further tests were carried out, including calcium carbonate content measurement, SEM observation, XRD tests, and FTIR tests on the soil samples. Both MICP and biochar are found to increase the calcium carbonate content in the soil. In the jointly solidified samples, calcium carbonate crystal aggregation is obvious. The cementation at the interface between biochar and soil particles is tighter. The porosity and unconfined compressive strength of the improved samples show a power function relationship. The results demonstrate that the combination of biochar and MICP technology has significant effects on silty clay solidification, and provide guidance for its application in engineering.