Enhancing the initial Coulombic efficiency (ICE) and cycling stability of silicon suboxide (SiO) anode is crucial for promoting its commercialization and practical implementation. Herein, we propose an economical and effective method for constructing pre-lithiated core–shell SiO anodes with high ICE and stable interface during cycling. The lithium silicon alloy (LiSi) is used to react with SiO in advance, allowing for improved ICE of SiO without compromising its reversible specific capacity. The pre-lithiated surface layer contains uniform multiphase lithium silicates (LSiO, LiSiO, and LiSiO) in the nanoscale. This multiphase lithium silicate layer exhibits mechanical robustness against variation of micro-stress, which can act as a buffer layer to relieve volume variation. In addition, analysis of dynamic electrochemical impedance spectroscopy (dEIS) and distribution of relaxation time (DRT) confirm that the multiphase lithium silicate layer enhances Li-ion diffusion kinetics and contributed to constructing stable SEI. As a result, the optimal L10-850 anode shows a high ICE of 85.3 %, together with a high specific capacity of 1771.5mAh mg. This work gives a perspective strategy to modify SiO anodes by constructing a pre-lithiated surface layer with practical application potentials.