A mild and efficient method was developed to prepare a microsized SiOx/C core-shell composite as anode material for lithium ion batteries. By mixing citric acid and ball-milled SiOx and subjecting them to carbonization, we obtained a uniform SiOx/C core-shell composite with a microsized SiOx core and conformal carbon shell. The carbon shell effectively enhanced the electrical conductivity of SiOx and mitigated the volume changes of SiOx during lithiation and delithiation. The SiOx/C composite electrode delivered a reversible specific capacity of 1296.3 mAh g(-1), coulombic efficiency of as high as 99.8%, and capacity retention of 65.1% (843.5 mAh g(-1)), even after 200 cycles. The composite also exhibited excellent rate capability. The approach is mild, mass-productive, and cost-effective and, thus, can be employed in large-scale production of high-performance SiOx/C composite anode material.