Spinel LiMn2O4 is a promising cathode candidate for lithium ion batteries whose electrochemical properties strongly depend on the surface orientation. In this work, we have successfully synthesized a high crystalline and well-defined truncated octahedral LiMn2O4 through the hydrothermal and heat treatment. The main {111} facets are aligned along the orientations mitigating Mn dissolution while the truncated {100} and {110} facets are along those facilitating Li+ diffusion. Benefiting from the unique structure, the octahedral LiMn2O4 delivers 143.4 mAh g−1 (close to the theoretical capacity of 148 mAh g−1) at 0.2 C and over 120 mAh g−1 at 30 C (discharged within 2 min) at 55 °C. Moreover, the fabricated LiMn2O4/Li4Ti5O12-TiO2 full cell demonstrates 121.6 mAh g−1 at 1 C and 56.0 mAh g−1 at 30 C with ∼81.2% capacity retention following 1000 cycles. The facilely synthesized truncated octahedral LiMn2O4 shows great potentials in practical applications for ultrafast and long-life lithium-ion batteries.