Lithium-rich layered cathodes are known famously for its superior capacity over traditional layered oxides but trapped for lower initial coulombic efficiency, poorer rate capability and worse cyclic stability in spite of diverse attempts. Herein, a new K-stabilized Li-rich layered cathode synthesized through a simple oxalate co-precipitation is reported for its super electrochemical performances. Compared with pristine Li-rich layered cathode, K-stabilized one reaches a higher initial coulombic efficiency of 87% from 76% and outruns for 94% of capacity retention and 244 mAh g-1 of discharge capacity at 0.5C after 100 cycles. Moreover, 133 mAh g-1 of discharge capacity can be delivered even charged at 10C showing a highly-improved rate capability. X-ray diffraction and electrochemical impedance spectroscopy tests show that enlarged Li slab layer caused by K+ accommodation can provide facile Li+ diffusion paths and facilitate Li+ migration from the crystal lattice. As a consequence, the introduction of K+ in the host layered structure can inhibit the detrimental spinel structure growth during cycling. Therefore, the K-stabilized Li-rich layered materials can be considered to be an attractive alternative to meet with the higher power and energy density demands of advanced lithium-ion battery.