3D flower-like NiO hierarchical architectures have been synthesized by a simple ethanolamine (EA)-mediated self-assembly route and subsequent calcination process. The synthesized β-Ni(OH)2 precursors annealed at 300, 400 and 500°C exhibit similar morphology by scanning electron microscopy and different crystallinity, surface area, and pore distribution via X-ray diffraction, Fourier transform infrared spectroscopy and nitrogen adsorption/desorption isotherms. The electrochemical properties indicate that the synthesized NiO hierarchical architectures annealed at 300°C show the best electrochemical performance, which presents a reversible specific capacity of 713mAhg−1 at a current density of 100mAg−1 after 40 cycles. With varying the rate from 100 to 1000mAg−1, the capacity still remains 580mAhg−1 at 500mAg−1 after 18 cycles and resumes to 470mAhg−1 at the same rate after 30 cycles. The above results indicate that the 3D flower-like NiO hierarchical architectures are promising anode materials for lithium ion batteries.