In situ incorporation of mesoporous Al₂O₃ (meso-Al₂O₃) into the MCM-41 extraframework without blocking the pores generates an ordered, long range and high surface area mesoporous support Al₂O₃–MCM-41 (AM). The mesoporous support surprisingly shows high surface area as compared to pristine MCM-41. The incorporation of meso-Al₂O₃ into the extraframework of MCM-41 through the silanol group is evidenced by FTIR, ²⁷Al MAS NMR and ²⁹Si MAS NMR spectroscopy. The result shows that Si/Al ratio 10 (AM 10) possesses improved textural properties as compared to AM 50 and AM 90. Iron is incorporated onto the surface of AM 10 in order to modify the surface property of AM 10, forming composite Fe/Al₂O₃–MCM-41 (Fe/AM 10). Characterization by small angle X-ray diffraction (SXRD), transmission electron microscopy (TEM), and N₂ adsorption–desorption measurements reveals that the mesoporous support and iron incorporated support possess large BET surface area (207–1244 m² g⁻¹), narrow pore size (2.4–2.7 nm) and high pore volume (0.370–2.37 cm³ g⁻¹). Among them, AM 10 shows highest surface area (1244 m² g⁻¹), narrow pore size (2.7 nm) and pore volume (2.37 cm³ g⁻¹). The incorporation effect of both meso-Al₂O₃ and iron in the formation of Fe/AM 10 has been well established by ²⁷Al MAS NMR spectroscopy. X-Ray photoelectron spectroscopy study confirms the 2+ state of iron in Fe/AM 10 and also establishes the incorporation of meso-Al₂O₃ and iron. Among the prepared mesoporous supports and different wt% of iron incorporated supports, it is seen that 5 Fe/AM 10 (‘5’ denotes the wt% of iron) has high adsorption as well as photo-Fenton degradation activity for MB. Moreover, 5 Fe/AM 10 is not merely a good adsorbent but also an efficient catalyst in the adsorption and photo-Fenton degradation (100%) of MB in 15 and 5 minutes, respectively. Furthermore, in the case of mixed cationic and anionic dyes (uniform mixture of methylene blue and methyl orange), MO adsorption and degradation (by photo-Fenton process) occur appreciably on the surface of MB through cationic–anionic interaction of MB and MO.