A cost-effective method is proposed to prepare a coal-derived hard carbon (HC) anode for sodium-ion batteries (SIBs) through pre-oxidation followed by post-carbonization. This process expands the d002 layer spacing, generates closed pores, and increases defect sites, leading to a HC anode with a balanced plateau and sloping capacity. The anode achieves a reversible capacity of 306.3 mAh·g⁻¹ at 0.03 A·g⁻¹ and 289 mAh·g⁻¹ at 0.1 A·g⁻¹, equivalent to 94.5% of the former. When integrated into a full cell, the HC anode demonstrates a high energy density of 410.6 Wh·kg⁻¹ (based on cathode mass). The study highlights the importance of precursor selection for commercializing HC anodes, as coal is a promising precursor due to its wide availability, low cost, and unique structure. However, coal-derived HC often has poor performance due to its microcrystalline structure and low carbon yield. Pre-oxidation is an effective strategy to prevent excessive graphitization and improve the microstructure of HC. The study successfully fabricates a coal-derived HC anode with favorable cost-efficiency and sodium storage capacity through pre-oxidation and post-carbonization. The introduction of oxygen functional groups enhances layer spacing, generates enclosed pores, and increases defect sites, leading to fast reaction kinetics and excellent rate performance. The HC anode shows great potential for practical application in SIBs. The results demonstrate that pre-oxidation is a simple, effective, and economical method to regulate the microstructure of coal-derived HC, which is crucial for the widespread use of SIBs anodes.A cost-effective method is proposed to prepare a coal-derived hard carbon (HC) anode for sodium-ion batteries (SIBs) through pre-oxidation followed by post-carbonization. This process expands the d002 layer spacing, generates closed pores, and increases defect sites, leading to a HC anode with a balanced plateau and sloping capacity. The anode achieves a reversible capacity of 306.3 mAh·g⁻¹ at 0.03 A·g⁻¹ and 289 mAh·g⁻¹ at 0.1 A·g⁻¹, equivalent to 94.5% of the former. When integrated into a full cell, the HC anode demonstrates a high energy density of 410.6 Wh·kg⁻¹ (based on cathode mass). The study highlights the importance of precursor selection for commercializing HC anodes, as coal is a promising precursor due to its wide availability, low cost, and unique structure. However, coal-derived HC often has poor performance due to its microcrystalline structure and low carbon yield. Pre-oxidation is an effective strategy to prevent excessive graphitization and improve the microstructure of HC. The study successfully fabricates a coal-derived HC anode with favorable cost-efficiency and sodium storage capacity through pre-oxidation and post-carbonization. The introduction of oxygen functional groups enhances layer spacing, generates enclosed pores, and increases defect sites, leading to fast reaction kinetics and excellent rate performance. The HC anode shows great potential for practical application in SIBs. The results demonstrate that pre-oxidation is a simple, effective, and economical method to regulate the microstructure of coal-derived HC, which is crucial for the widespread use of SIBs anodes.