Zeolites have been widely used for heavy metal removal due to their high cation exchange capacity and surface sorption properties. However, the empirically determined adsorption capacity trend of Pb2+ > Cu2+ > Ni2+ was not well understood. Herein, we discovered that the adsorption of Ni2+ by zeolites was greatly influenced by hierarchical pore geometry, while the adsorption of Pb2+ or Cu2+ was dependent on cation exchange determined by the framework composition. This difference in adsorption mechanisms is manifested through the systematic study of heavy metal adsorption using low-silica LTA and FAU zeolites with different mesopore architectures and compositions. Synthesizing mesoporous zeolite A of MLTA-P using proline mesoporogen considerably enhanced the Ni2+ adsorption capacity to more than twice of that of conventional zeolite A synthesized without organics, while the adsorption capacities for Cu2+ and Pb2+ were almost unaltered at similar to 170 and 510 mg/g. The study on the effect of zeolite synthesis time and adsorbate pH value revealed the significant influence of zeolite crystallinity, surface hydroxyl group, and hierarchical pore architecture on the Ni2+ uptake. The MLTA-P zeolite showed higher stability against pH variation in acid range and remarkably enhanced uptake in alkaline conditions, reaching 218 mg/g at a pH of 11. The full characterization of the adsorbent by scanning electron microscopy and X-ray photoelectron spectroscopy indicated the involvement of the surface reaction forming Ni phyllosilicate nanosheet species during the nickel metal removal process in which transport limitation played a crucial role. The uptake kinetics and isotherms could be perfectly reflected by a pseudo-secondorder rate equation and the Langmuir model, confirming the nature of chemisorption.