Abstract: The preparation and hydrogen storage performance of porous biochar materials derived from different anatomical parts of corn stalks—namely leaf, stem bark, and stem pith—are investigated. From an interdisciplinary perspective integrating plant histology and material structure evolution, an innovative precursor regulation strategy based on plant tissue differences is proposed, systematically revealing the pivotal role of raw material tissue characteristics in determining the structural development and hydrogen storage performance of biomass-derived carbon materials. Through a stepwise correlation established between compositional differences, microstructure, pore characteristics, and adsorption behavior, the profound influence mechanism of precursor tissue type on material properties is clarified, providing theoretical support for constructing a clear "precursor–structure–performance" relationship. The results demonstrate that the tissue origin of the raw material plays a key role in the pore formation mechanism. Owing to its chemical composition characterized by high hemicellulose and low lignin content, the stem pith facilitates the formation of a highly disordered and easily etchable carbon framework during activation. This ultimately leads to the construction of a well-developed microporous network with a specific surface area of 3 723.8 m²/g and a micropore volume of 1.57 cm³/g, where pore sizes are concentrated in the ideal range of 0.7–1.0 nm for hydrogen storage, demonstrating significant structural advantages. Benefiting from this optimized structure, a maximum hydrogen storage capacity of 4.12% is achieved at 77 K, which is further enhanced to 5.54% under 5.0 MPa pressure. In contrast, the leaf- and bark-derived carbon materials show relatively lower pore development and hydrogen storage performance due to differences in lignin content. Through a systematic investigation of the chemical composition of different corn stalk tissues and the resultant material microstructures, the regulatory mechanism of precursor characteristics on the hydrogen storage performance of porous carbons is revealed, indicating that micropore volume and pore size distribution are key factors influencing low-temperature hydrogen storage capacity. This work provides new insights and a theoretical foundation for the high-value utilization of agricultural waste and the design of high-performance porous carbon materials for hydrogen storage.