A FeCoNiCrTi high-entropy alloy (HEA) nanosheet was synthesized via a wet chemical ball milling method and introduced into MgH₂ to enhance its hydrogen storage performance. The HEA showed superior catalytic activity for MgH₂, reducing the initial desorption temperature from 330.0 to 198.5 °C and decreasing the dehydrogenation activation energy by 51%. The MgH₂-HEA composite required only one-twentieth the amount of hydrogen compared to pure MgH₂ to absorb 5.0 wt% H₂ at 225 °C. The synergistic effect of the "hydrogen pumping" effect from Mg₂Ni/Mg₂NiH₄ and Mg₂Co/Mg₂CoH₅ couples, along with the good dispersion of Fe, Cr, and Ti on MgH₂, contributed to the enhanced de/hydrogenation performance. This study provides important guidance for designing and fabricating multiple transition metal catalysts and may advance the commercial application of magnesium-based hydrides. The introduction of HEA into MgH₂ improves its hydrogen storage performance by enhancing the thermodynamics and kinetics of MgH₂. HEA can modulate the thermodynamic properties of MgH₂ by forming intermetallic hydrides such as Mg₂NiH₄, Mg₂CoH₅, and Mg₂FeH₆. The "hydrogen gateway" effect during hydrogen storage reactions can further boost the dissociation and reassembly of the Mg-H bond. Wet chemical ball milling plays a significant role in regulating the performance of catalysts. In this study, FeCoNiCrTi HEA, composed of non-precious metals, was used to tune the catalytic activity. The performance of differently treated alloys was compared, and the best-optimized method was selected for further study. The alloy showed promising catalytic efficiency and stability in improving the hydrogen storage properties of MgH₂. The in situ formed Mg₂NiH₄ and Mg₂CoH₅ during the reaction, along with the generated γ-MgH₂ phase during the ball milling process, effectively lowered the initial hydrogen release temperature of the whole system.A FeCoNiCrTi high-entropy alloy (HEA) nanosheet was synthesized via a wet chemical ball milling method and introduced into MgH₂ to enhance its hydrogen storage performance. The HEA showed superior catalytic activity for MgH₂, reducing the initial desorption temperature from 330.0 to 198.5 °C and decreasing the dehydrogenation activation energy by 51%. The MgH₂-HEA composite required only one-twentieth the amount of hydrogen compared to pure MgH₂ to absorb 5.0 wt% H₂ at 225 °C. The synergistic effect of the "hydrogen pumping" effect from Mg₂Ni/Mg₂NiH₄ and Mg₂Co/Mg₂CoH₅ couples, along with the good dispersion of Fe, Cr, and Ti on MgH₂, contributed to the enhanced de/hydrogenation performance. This study provides important guidance for designing and fabricating multiple transition metal catalysts and may advance the commercial application of magnesium-based hydrides. The introduction of HEA into MgH₂ improves its hydrogen storage performance by enhancing the thermodynamics and kinetics of MgH₂. HEA can modulate the thermodynamic properties of MgH₂ by forming intermetallic hydrides such as Mg₂NiH₄, Mg₂CoH₅, and Mg₂FeH₆. The "hydrogen gateway" effect during hydrogen storage reactions can further boost the dissociation and reassembly of the Mg-H bond. Wet chemical ball milling plays a significant role in regulating the performance of catalysts. In this study, FeCoNiCrTi HEA, composed of non-precious metals, was used to tune the catalytic activity. The performance of differently treated alloys was compared, and the best-optimized method was selected for further study. The alloy showed promising catalytic efficiency and stability in improving the hydrogen storage properties of MgH₂. The in situ formed Mg₂NiH₄ and Mg₂CoH₅ during the reaction, along with the generated γ-MgH₂ phase during the ball milling process, effectively lowered the initial hydrogen release temperature of the whole system.