The widespread use of silicon oxycarbide (SiOC) anodes in industry has been hampered by their limited reversible capacity, subpar rate performance, and complex manufacturing methods. In this research, a novel strategy is proposed to in situ construct SiOC with oxygen-rich structural units and flake morphology via one-pot synthesis, which integratively facilitates the reversible capacity and enhances the transport capability of Li+. Benefiting from these structural and compositional merits, the produced SiOC electrode showcases an impressive reversible capacity of 906 mAh g−1 at 0.1 A g−1, a remarkable rate capability of 591 mAh g−1 and cycling stability of 98 % capacity retention rate at 2.0 A g−1 after 1200 cycles. Characterization results prove that the SiOC with a higher content of oxygen-rich structural units and flakes is helpful in forming the stable solid-electrolyte interface film and buffering volume expansion. Furthermore, it is demonstrated that the SiOC anodes containing LixSiOy compounds reduce the irreversible use of Li-ions during the initial reaction. Our findings present an effective method to simultaneously manipulate the structural units and morphology of SiOC compounds, paving the way for superior electrochemical performance.