A novel magnetic composite with hierarchically porous nature is prepared by a facile synthetic strategy for the highly toxic chromium (Cr(VI)) removal. The magnetic NMPC@mSiO 2 with defined mesoporous shell is successfully fabricated by one-step carbonization of ZIF-67@mSiO 2 , which is prepared through a simple one-pot method. Benefiting from the protection of mSiO 2 during pyrolysis process, NMPC@mSiO 2 -800 owns high specific surface area, hierarchically porous structure and increased C–N content. It shows an excellent Cr(VI) removal performance with an adsorption capacity rising to 158.11 mg·g −1 from 78.60 mg·g −1 (NMPC-800). Moreover, the prepared NMPC@mSiO 2 -800 exhibits antijamming capability for Cl −1 /SO 4 2− with a negligible adverse impact on Cr(VI) removal. The kinetic studies show that the Cr(VI) removal on NMPC@mSiO 2 -800 confirms to pseudo-second-order model equipped with a relatively large adsorption rate constant, revealing the ability to quickly adsorb Cr(VI). The thermodynamic parameters manifest Cr(VI) adsorption is spontaneous and endothermic. Besides, the NMPC@mSiO 2 -800 can be quickly recovered from the system due to the magnetic porous carbon. Herein, NMPC@mSiO 2 -800 has a broad application prospect in Cr(VI) removal due to its excellent adsorption capacity, good antijamming ability, high adsorption rate and easy magnetic separation. • The hierarchically nitrogenous porous carbon is prepared by mSiO 2 -protected calcination. • The Cr(VI) adsorption capacity of NMPC@SiO 2 -800 is improved due to mSiO 2 coating. • NMPC@mSiO 2 -800 achieves more than 90% equilibrium adsorption capacity in 5 min. • The adsorption process is dominated by reduction.