Herein, ultrasmall nanostructured Co3O4 particles have been prepared by a facile two-step synthetic method and furthermore applied to lithium-ion batteries. Benefitting from an increased specific surface area and improved tolerance for volume expansion, they deliver an extremely high specific capacity of 1432.7 mA h g-1 at 0.1 A g-1 and an outstandingly long cycle life with about 511.2 mA h g-1 at 10 A g-1 after 2000 cycles. This work will pave a new way to engineer advanced electrode materials for long-lived high-rate lithium-ion batteries.