This study sought to use tropical almond leaves (TALs) for the simple fabrication of iron-containing activated carbon (IAC). Iron precursor (FeCl3) and activating agent (KOH) were sequentially preloaded in TALs. One-pot pyrolysis then generated iron-based particles (8.7 wt%), mainly metallic iron crystals, within AC support. The specific saturation magnetization of IAC was measured to be 48.9 emu/g, highlighting its ability to be efficiently separated using external magnetic fields. Moreover, the activation process yielded IAC with a large total volume of 0.28 cm3/g and a high specific surface area of 463 m2/g. Accordingly, IAC was investigated as an oxidation catalyst to degrade methylene blue (MB) by H2O2. At pH 3.0, 800 ppm H2O2, and 0.10 g/L IAC, 95.3% of MB (200 ppm) was removed after 30 min of adsorption and 60 min of oxidation. Altogether, iron-containing activated carbon from fallen leaves of tropical almonds proved its potential for robust methylene blue degradation by H2O2.