This　short　communication　investigates　the　involvement　of　polypropylene　fibers　in　the　biocarbonated　reactive　magnesia　cement　mixes　to　improve　the　splitting　tensile　strength　of　sand　for　soil　improvement.　By　varying　the　RMC　content　(5　and　10%　by　weight　of　sand)　and　fiber　content　(0,　0.5,　and　1%　by　weight　of　sand),　a　suitable　mix　design　was　determined.　The　test　results　showed　that　the　peak　tensile　strength　of　biocarbonated　RMC-based　sand　samples　with　an　optimum　fiber　content　of　1%　could　improve　by　more　than　4　times　compared　to　the　biocarbonated　sand　without　fiber　reinforcement.　This　was　attributed　to　the　generation　of　hydrated　magnesium　carbonates　with　the　microbially　induced　CO2/carbonate　process,　bonding　the　fiber–matrix　and　eliminating　the　brittleness,　consequently　enhancing　the　tensile　ductility　of　biocarbonated　sand.　©　2022,　The　Author(s),　under　exclusive　licence　to　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature.