Hydrogen storage and biogas slurry treatment are critical challenges in the energy transition. This study introduces a novel approach for synthesizing hollow porous carbon spheres from biogas slurry to meet the demands for solid-state hydrogen storage. Using an α-Fe2O3 hard template method, large hollow spheres were formed, and after KOH etching, micropores and mesopores were enriched in the sphere shell, creating a hierarchical pore structure. Under optimized activation conditions, material D75-6 demonstrated a high surface area of 3134 m2/g and microporosity of 88 %, achieving a gravimetric capacity of 6.73 wt% (50 bar) and a volumetric capacity of 25.93 g/L (30 bar) at 77 K. These values not only surpass the DOE’s target of 6.5 wt% on a material level, but also demonstrate a significant advantage over traditional carbon materials (<6 wt%) and benchmark MOFs (9–17 g/L), offering a cost-effective alternative to high-pressure tanks. Additionally, the hierarchical pore structure facilitates rapid H2 diffusion, leading to accelerated adsorption/desorption kinetics in 121/90 s. This research provides a strategy for waste resource utilization and presents a comprehensive study on the hydrogen storage performance of the derived materials, with significant implications for both biogas and hydrogen engineering.