Hexavalent chromium (Cr(VI)) is a typical carcinogenic contaminant, and the prerequisite for its efficient remediation is the low-cost and high-efficiency removal materials. Thus, in this study, we propose an outstanding Cr(VI) removal iron-based materials derived from the self-modification of secondary minerals by simple pyrolysis and explore their Cr(VI) removal mechanism. The resulting materials, C-AJ (from ammoniojarosite) and C-Jar (from jarosite) exhibited excellent Cr(VI) removal efficiencies, with maximum Cr(VI) removal capacities of 96.9 mg/g and 70.7 mg/g, respectively. Their excellent Cr(VI) removal capacities are mainly attributed to the self-modification of two minerals to form Fe(II) and the retained SO