This study investigates the thermal and mechanical performance of concrete modified with two types of biomass-derived biochar: carbonized coconut shell powder and carbonized Chinese fir powder. Biochar is incorporated as an additive at 5%, 7% and 10% of the cement weight, without reducing the cement content. The compressive strength, thermal conductivity, and specific heat capacity of each mix were evaluated after 28 days of standard curing. Results indicate that the effect of biochar on compressive strength is related to its dosage and type. While a 7% dosage of coconut shell biochar improved compressive strength to 37.42 MPa, exceeding the reference mix (35.40 MPa), a 10% dosage of Chinese fir biochar significantly reduced it to 27.90 MPa. Thermal conductivity decreased in all biochar-modified mixes, with the lowest value of 0.05483 W/m·K observed in the 10% coconut shell group, representing a 48% reduction compared to the control. Specific heat capacity also increased with higher biochar content, reaching a maximum of 0.982 J/g·°C in the 10% fir biochar group. These improvements are attributed to the high porosity, low density, and insulating characteristics of biochar. Overall, the findings highlight the potential of biochar as an effective and sustainable additive to enhance the thermal regulation capacity of concrete, supporting its use in energy-efficient and multifunctional building materials.