•Large scale production of monocrystalline Heusler micro-wire is reported.•Such a wire is characterized by well oriented anisotropy.•Half-metallic behaviour is observed in the low temperature range. Large scale production of single crystalline phase of Heusler Co2FeSi alloy microwire is reported. The long microwire (∼1 km) with the metallic nucleus diameter of about 2 µm is characterized by well oriented monocrystalline structure (B2 phase, with the lattice parameter a = 5.615 Å). Moreover, the crystallographic direction 101 is parallel to the wire’s axis along the entire length. Additionally, the wire is characterized by exhibiting a high Curie temperature (Tc > 800 K) and well-defined magnetic anisotropy mainly governed by shape. Electrical resistivity measurement reveals the exponential suppression of the electron-magnon scattering which provides strong evidence on the half-metallic behaviour of this material in the low temperature range.