Dendritic challenges in Li metal batteries are commonly resolved using porous three-dimensional (3D) current collectors, which have a significant issue in that Li is deposited from the top (top growth) of the structure rather than from the bottom (bottom growth), failing to effectively suppress dendrite growth and volumetric expansion. We propose the structure incorporating a gradient lithiophilic seed within a 3D framework by pulse electroplating Mg, specifically targeting the near bottom, to promote bottom growth and achieve dense Li deposition. This method achieves precise control over the catalytic seed size and distribution. Optimal conditions for maximizing catalytic effect are identified. The resulting Mg-gradient porous-Cu structure exhibits superior Li-plating behavior with bottom growth, significantly reducing dendrite formation and improving cycle life. The mechanistic origin of bottom-guided Li growth is supported by DFT and 3D simulation results. This method presents a significant step forward in developing high-performance Li-metal batteries.