The spinel oxide LiV2O4 is a interesting compound that shows heavy fermion behaviour despite its d-electron system. The large quasiparticle specific heat coefficient (gamma value) is close to those of other heavy fermion systems in f-electron Zintl compounds. The mechanism of such heavy fermion behaviour in LiV2O4 has not been resolved, owing to the lack of high-quality single crystals required for experiments. Here we present a crystal-growth technique for LiV2O4 using a solvent system that acts effectively for mixed-valence vanadium (V3+ and V4+) oxides. The grown crystals have a well-developed octahedral form bounded by {111} faces, with high crystallographic quality and maximum size of almost 1.0x1.0x1.0 mm. The crystals have stoichiometric composition and show heavy fermion behaviour with an extremely large gamma value of similar to 460 mJ mol(-1) K-2. Crystals of LiV2O4 are very sensitive to air and moisture, but are stable up to 1,020 degrees C under vacuum.