Abstract: Biomass-derived hard carbon is a promising anode material for sodium-ion batteries; however, its poor cycling stability significantly limits practical applications. In this work, camellia oleifera shells and petroleum pitch were employed as precursors to fabricate a soft–hard composite carbon. During carbonization, the pitch functions as a filler to regulate the pore structure and simultaneously introduces heteroatoms.The results show that, at a camellia shell-to-pitch mass ratio of 8∶1 (denoted as SHC-8), the material delivers an initial charge capacity of 325.5 mA·h/g at a current density of 30 mA/g, with a low-voltage plateau capacity of 229 mA·h/g. The plateau capacity contribution increases from 61.8% to 70.3%, and a capacity retention of 96.4% is achieved after 100 cycles. Even at a high current density of 1000 mA/g, a reversible capacity of 167.5 mA·h/g is maintained after 500 cycles. Structural characterizations indicate that co-carbonization substantially reduces the specific surface area while increasing the nitrogen and oxygen contents, which effectively suppresses interfacial side reactions and enhances sodium storage behavior in the low-voltage region. This study provides a viable strategy for optimizing biomass-derived hard carbon anodes, demonstrating considerable potential for improving cycling stability and rate capability.