jats:p Peat is a soft soil with a very high organic content, which makes it highly susceptible to extreme differential settlement. Although cement stabilisation is highly effective, it is not common practice due to the high cost of treatment associated with a high binder dosage required. The use of a novel material, biochar, as a potential replacement for cement and an alternative filler to sand was investigated in this work. Biochar is more sustainable than traditional construction materials and has carbon dioxide sequestration ability. It could also potentially be cheaper than cement or sand, depending on the source of feedstock used. Cement-treated peat with sand was used as a benchmark to assess the performance of biochar-enhanced cement-treated peat. The samples with biochar finer than 75 μm performed better than the sand equivalent, with over 50% increase in compressive strength. Furthermore, it was found that the samples with 100 kg/mjats:sup3</jats:sup> cement and 400 kg/mjats:sup3</jats:sup> biochar had comparable performance to the control sample with 200 kg/mjats:sup3</jats:sup> cement only, without biochar, highlighting the potential of biochar to partially replace cement. Scanning electron microscopy and X-ray diffraction results showed that the mechanisms behind the performance gain in biochar samples are of both mechanical and chemical nature. </jats:p>